html5/spec-ja/workers-non-normative.ja.html.u8

<!DOCTYPE html><html lang=en-US-x-hixie><meta charset=ascii><title>Web Workers</title><link href=http://www.whatwg.org/style/specification rel=stylesheet>
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   <p class="has-ja-translation" data-ja-hash="7c0cfd95ed2e5f66067c25a5e7fec67c"><span class=en-original lang=en><a class=logo href=http://www.whatwg.org/ rel=home><img alt=WHATWG src=/images/logo></a></span><span class=ja-translation lang=ja><a class=logo href=http://www.whatwg.org/ rel=home><img lang=en alt=WHATWG
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   <h1 class="no-ja-translation" data-ja-hash="6cb7eb9696d986359fa3a78c4b8e60dc"><span class=en-original lang=en>Web Workers</span></h1>
   <h2 class="no-num no-toc has-ja-translation" data-ja-hash="1b2364916e1ba9764051007c2217f175" data-ja-real-hash="49e1912aba8596df1680312d23b3e796" id=draft-recommendation-&mdash;-16-september-2009><span class=en-original lang=en>Draft Recommendation &mdash; 16 September 2009</span><span class=ja-translation lang=ja>勧告案<ins class=ja-note>の非公式和訳</ins> &mdash; 
<ins class=ja-note>(原文出版日)</ins> 2009年9月16日</span></h2>
   <p class="has-ja-translation" data-ja-hash="5211c3fce4ddd8160d21446a73a092c1"><span class=en-original lang=en>You can take part in this work. <a href=http://www.whatwg.org/mailing-list>Join the working group's discussion list.</a></span><span class=ja-translation lang=ja>みなさんにも作業にご参加いただけます。 <a
    href=http://www.whatwg.org/mailing-list>作業部会の議論用メイリング・リストに参加してください。</a></span></p>
   <p class="has-ja-translation" data-ja-hash="f8e7b0fcec0268c81579638290279e82"><span class=en-original lang=en><strong>Web designers!</strong> We have a <a href=http://blog.whatwg.org/faq/>FAQ</a>, a <a href=http://forums.whatwg.org/>forum</a>, and a <a href=http://www.whatwg.org/mailing-list#help>help mailing list</a> for you!</span><span class=ja-translation lang=ja><strong>Web デザイナーのみなさん!</strong> みなさんのための <a
    href=http://blog.whatwg.org/faq/ lang=en>FAQ</a>、<a
    href=http://forums.whatwg.org/>掲示板</a>、<a
    href=http://www.whatwg.org/mailing-list#help>ヘルプ用メイリング・リスト</a>があります!

</span><p>

<!-- Japanese-translation-only notes -->
<ins class="ja-note cover-ja-note" lang=ja>
<p>この文書は、 WHATWG 仕様書の日本語訳です。 正式な仕様書は英語版だけであり、この日本語訳はあくまで参考としてご利用ください。

<p lang=en>This document is a non-normative Japanese translation of the WHATWG specification. Only the original English version is normative and this Japanese translation is non‐normative.

<p>日本語訳は段落をダブルクリックすると編集できます。<a href="http://suika.fam.cx/~wakaba/pbin/accounts/add">アカウントを作成</a>して <code>spec-ja</code> グループに参加してください。編集結果はおよそ3時間おきに反映されます。また、原文の変更には毎日自動的に追随しています。 (<a href=notes>詳細</a>)

<p lang=en>You can edit Japanese text by double-clicking the paragraph you'd like to edit.  <a href="http://suika.fam.cx/~wakaba/pbin/accounts/add">Create an account</a> and join the <code>spec-ja</code> group.  Any additions of and modifications to Japanese text will be applied to the document within about three hours. Any changes to the original English specification will automatically be incorporated to the document every day. (<a href=notes>Details</a>)

<p><a href="http://wiki.whatwg.org/wiki/Translations">他の翻訳のリスト</a>もご覧ください。

<p lang=en>See also the list of <a href="http://wiki.whatwg.org/wiki/Translations">translations</a>.

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<p><span><!-- dummy --></span></p>
   <dl><dt class="has-ja-translation" data-ja-hash="87b044fafc6f01197a9a700e6fa28a69"><span class=en-original lang=en>This version:</span><span class=ja-translation lang=ja><ins class=ja-note>原文の</ins>この版</span></dt>
    <dd class="no-ja-translation" data-ja-hash="b1b00adfdf359bf303bf8c64476f2e91"><span class=en-original lang=en><a href=http://www.whatwg.org/specs/web-workers/current-work/>http://whatwg.org/ww</a></span></dd>
    <dt class="has-ja-translation" data-ja-hash="8866e8de2efa7275a5dc8e942c1613c2"><span class=en-original lang=en>Version history:</span><span class=ja-translation lang=ja><ins class=ja-note>原文の</ins>改版履歴:</span></dt>
    <dd class="has-ja-translation" data-ja-hash="fc2cb84da44565f149b710ac5dfb38f2"><span class=en-original lang=en>Twitter messages (non-editorial changes only): <a href=http://twitter.com/WHATWG>http://twitter.com/WHATWG</a></span><span class=ja-translation lang=ja><span lang=en>Twitter</span> メッセージ (編集上の変更以外): <a
     href=http://twitter.com/WHATWG>http://twitter.com/WHATWG</a></span></dd>
    <dd class="has-ja-translation" data-ja-hash="3a0facbd53f73c0877af4c6485a783af"><span class=en-original lang=en>Commit-Watchers mailing list: <a href=http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org>http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a></span><span class=ja-translation lang=ja>Commit-Watchers メイリング・リスト: <a
href=http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org>http://lists.whatwg.org/listinfo.cgi/commit-watchers-whatwg.org</a></span></dd>
    <dd class="has-ja-translation" data-ja-hash="5e1dbca74cface6f0d0ea523340e6a89" data-ja-real-hash="a5d87a842e49eed08d894d0148296604"><span class=en-original lang=en>Interactive Web interface: <a href=http://html5.org/tools/web-workers-tracker>http://html5.org/tools/web-workers-tracker</a></span><span class=ja-translation lang=ja>対話的 <span lang=en>Web</span> 界面: <a href=http://html5.org/tools/web-workers-tracker>http://html5.org/tools/web-workers-tracker</a></span></dd>
    <dd class="has-ja-translation" data-ja-hash="ea5cbdd06bfb529e4a1bcfeac9cfbd61" data-ja-real-hash="fabeffa34fbe319f499e2c5fd49a414f"><span class=en-original lang=en>Subversion interface: <a href=http://svn.whatwg.org/webworkers/>http://svn.whatwg.org/webworkers/</a></span><span class=ja-translation lang=ja><span lang=en>Subversion</span> 界面: <a href=http://svn.whatwg.org/webworkers/>http://svn.whatwg.org/webworkers/</a></span></dd>
    <dt class="has-ja-translation" data-ja-hash="8468b55db22971120cb71091ece7839e"><span class=en-original lang=en>Issues:</span><span class=ja-translation lang=ja>問題:</span></dt>
    <dd class="has-ja-translation" data-ja-hash="80e92f8cfebdeaa7dd35236fded506f7"><span class=en-original lang=en>To send feedback: <a href=http://www.whatwg.org/mailing-list>[email protected]</a></span><span class=ja-translation lang=ja>フィードバックの送信先: <a
     href=http://www.whatwg.org/mailing-list>[email protected]</a></span></dd>
    <dd class="has-ja-translation" data-ja-hash="31c70a584b8b4195d95daffc76736dea"><span class=en-original lang=en>To view and vote on feedback: <a href=http://www.whatwg.org/issues/>http://www.whatwg.org/issues/</a></span><span class=ja-translation lang=ja>フィードバックの閲覧・投票: <a
     href=http://www.whatwg.org/issues/>http://www.whatwg.org/issues/</a></span></dd>
    <dt class="has-ja-translation" data-ja-hash="aa8d072dc59504320cfa92381f541a5f"><span class=en-original lang=en>Editor:</span><span class=ja-translation lang=ja>編集者:</span></dt>
    <dd class="no-ja-translation" data-ja-hash="220fb2ab7924ad62bc8567b8b9c5f0f8"><span class=en-original lang=en>Ian Hickson, Google, [email protected]</span></dd>
   </dl><p class="copyright no-ja-translation" data-ja-hash="01887da059d5ef35df4e1cc221f80391"><span class=en-original lang=en>&copy; Copyright 2004-2008 Apple Computer, Inc.,
   Mozilla Foundation, and Opera Software ASA.</span></p>
   <p class="copyright no-ja-translation" data-ja-hash="5419c8afab07265f61a6768f2680776d"><span class=en-original lang=en>You are granted a license to use, reproduce
   and create derivative works of this document.</span></p>
  </div>

  <hr><h2 class="no-num no-toc has-ja-translation" data-ja-hash="e353dbe42c8654f33588d4da0b517469" id=abstract><span class=en-original lang=en>Abstract</span><span class=ja-translation lang=ja>概要</span></h2>

  <p class="has-ja-translation" data-ja-hash="a4f61aa99f0d87d5d87b6e07071a74da"><span class=en-original lang=en>This specification defines an API that allows Web application
  authors to spawn background workers running scripts in parallel to
  their main page. This allows for thread-like operation with
  message-passing as the coordination mechanism.</span><span class=ja-translation lang=ja>この仕様書は、 Web アプリケーションで、主たる頁とは並列に、
背景労働者スクリプトを走らせるための API を定義します。
これにより、メッセージ・パッシングによるスレッド的操作を協調機構として利用できるようになります。</span></p>


  <h2 class="no-num no-toc has-ja-translation" data-ja-hash="c9bfd146532700356f3ff5ea6b1bf72e" id=status><span class=en-original lang=en>Status of this document</span><span class=ja-translation lang=ja>この文書の状態</span></h2>

  <p class="has-ja-translation" data-ja-hash="910f4ff57cc374ba46a8fecb18849de5"><span class=en-original lang=en><strong>This is a work in progress!</strong> This document is
  changing on a daily if not hourly basis in response to comments and
  as a general part of its development process. Comments are very
  welcome, please send them to <a href=mailto:[email protected]>[email protected]</a>. Thank
  you.</span><span class=ja-translation lang=ja><strong>この文書は作業中です!</strong>
この文書は、コメントへの対応や通常の開発の過程として、
毎時毎分とは言い過ぎですが毎日のペースで変更されています。
コメントは非常に歓迎していますので、
<a href=mailto:[email protected]>[email protected]</a>
へお送りください。よろしくお願いします。</span></p>

  <p class="has-ja-translation" data-ja-hash="5bb9ea777b965ca8d962ba2b6f663d46"><span class=en-original lang=en>The current focus is in developing a first draft proposal.</span><span class=ja-translation lang=ja>現在の焦点は、第1案の開発です。</span></p>

  <p class="has-ja-translation" data-ja-hash="f0a0e89202a0b75b7cf2314905ae258d"><span class=en-original lang=en>Implementors should be aware that this specification is not
  stable. <strong>Implementors who are not taking part in the
  discussions are likely to find the specification changing out from
  under them in incompatible ways.</strong> Vendors interested in
  implementing this specification before it eventually reaches the
  call for implementations should join the <a href=/mailing-list>WHATWG mailing list</a> and take part in the
  discussions.</span><span class=ja-translation lang=ja>実装者は、この仕様書が安定していないことに注意するべきです。
<strong>実装者は議論に参加しておかないと、
仕様がその実装とは非互換に変更されてしまうかもしれません。</strong>
この仕様書がいずれ実装呼び掛けの段階に達するのよりも前にこの仕様を実装したい販売者は、
<a href=http://www.whatwg.org/mailing-list>WHATWG メイリング・リスト</a>に参加し、
議論に加わるべきです。</span></p>

  <p class="no-ja-translation" data-ja-hash="739dc8d532ab9ebbd8a5ba09015898cc"><span class=en-original lang=en>This specification is also being produced by the <a href=http://www.w3.org/2008/webapps/>W3C Web Apps WG</a>. The two
  specifications are identical from the table of contents onwards.</span></p>

  <h2 class="no-num no-toc has-ja-translation" data-ja-hash="598b8ae10dfce818e73d3218daddbdae" id=contents><span class=en-original lang=en>Table of contents</span><span class=ja-translation lang=ja>目次
</span></h2>
  
<!--begin-toc-->
<ol class=toc>
 <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="e8340d3e813afc18cffdf99dd3a546e3"><span class=en-original lang=en><a href=#introduction><span class=secno>1 </span>Introduction</a>
  </span><ol>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="1f928c91e5f5cc18f353953a9057c45e"><span class=en-original lang=en><a href=#scope><span class=secno>1.1 </span>Scope</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="d9aa6a9a8b1af17de823ae3bc43e4cfa"><span class=en-original lang=en><a href=#tutorial><span class=secno>1.2 </span>Tutorial</a>
    </span><ol>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="4cc3646bed3970b883d0e3670dc846be"><span class=en-original lang=en><a href=#a-background-number-crunching-worker><span class=secno>1.2.1 </span>A background number-crunching worker</a></span></li>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="d6b18f36ab82a61c165ccf567ef56b09"><span class=en-original lang=en><a href=#a-worker-for-updating-a-client-side-database><span class=secno>1.2.2 </span>A worker for updating a client-side database</a></span></li>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="5d6e6c3a38a06321f9ff944393eb85c8"><span class=en-original lang=en><a href=#worker-used-for-background-i/o><span class=secno>1.2.3 </span>Worker used for background I/O</a></span></li>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="00a7ff1b4687e65bfd54d8f34ac6c51b"><span class=en-original lang=en><a href=#shared-workers><span class=secno>1.2.4 </span>Shared workers</a></span></li>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="0165a00ce6ba433bb49fb40d83e80072"><span class=en-original lang=en><a href=#delegation><span class=secno>1.2.5 </span>Delegation</a></span></li>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="b073b1b0d03d81d0427c4bbb5a1056dc"><span class=en-original lang=en><a href=#providing-libraries><span class=secno>1.2.6 </span>Providing libraries</a></span></ol></ol></li>
 <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="adf81d9200d74ed3c0f2c032a0531bf6"><span class=en-original lang=en><a href=#conformance-requirements><span class=secno>2 </span>Conformance requirements</a>
  </span><ol>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="b161941cca2282efa472ccf0fc205795"><span class=en-original lang=en><a href=#dependencies><span class=secno>2.1 </span>Dependencies</a></span></ol></li>
 <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="50b097cb49254c35d708954ba4f90f62"><span class=en-original lang=en><a href=#terminology><span class=secno>3 </span>Terminology</a></span></li>
 <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="211638ee3831cd03e9865c803584d48d"><span class=en-original lang=en><a href=#infrastructure><span class=secno>4 </span>Infrastructure</a>
  </span><ol>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="f3f7863eb788bc470f20764d323ff03a"><span class=en-original lang=en><a href=#the-global-scope><span class=secno>4.1 </span>The global scope</a>
    </span><ol>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="07444422623a61768c995caee39d6f3f"><span class=en-original lang=en><a href=#the-workerglobalscope-abstract-interface><span class=secno>4.1.1 </span>The <code>WorkerGlobalScope</code> abstract interface</a></span></li>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="ffb909cb8c908fc02c8383085a89f4b3"><span class=en-original lang=en><a href=#dedicated-workers-and-the-dedicatedworkerglobalscope-interface><span class=secno>4.1.2 </span>Dedicated workers and the <code>DedicatedWorkerGlobalScope</code> interface</a></span></li>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="4ce24e9ab32d066fc7ea5182fd496649"><span class=en-original lang=en><a href=#shared-workers-and-the-sharedworkerglobalscope-inteface><span class=secno>4.1.3 </span>Shared workers and the <code>SharedWorkerGlobalScope</code> inteface</a></span></ol></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="10cadfd4dee0f6d90bce2e454a454935"><span class=en-original lang=en><a href=#origins-of-workers><span class=secno>4.2 </span>Origins of workers</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="1e7058220085c30c6bb2a12a3c89679e"><span class=en-original lang=en><a href=#decoding-scripts><span class=secno>4.3 </span>Decoding scripts</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="e2bf69c265f0577e8eda8540795eac46"><span class=en-original lang=en><a href=#the-event-loop><span class=secno>4.4 </span>The event loop</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="2b43c40d7feeeee8ea12fd0c23d99809"><span class=en-original lang=en><a href="#the-worker's-lifetime"><span class=secno>4.5 </span>The worker's lifetime</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="5446f38a420881f029c7a587e3b49523"><span class=en-original lang=en><a href=#processing-model><span class=secno>4.6 </span>Processing model</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="d8bba28047e39857c758bfb25576078e"><span class=en-original lang=en><a href=#runtime-script-errors><span class=secno>4.7 </span>Runtime script errors</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="e415bb73deb1eb37d58b2c426c2891bf"><span class=en-original lang=en><a href=#creating-workers><span class=secno>4.8 </span>Creating workers</a>
    </span><ol>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="fd7fce5cf761f81e7ccde31c886c4e88"><span class=en-original lang=en><a href=#the-abstractworker-abstract-interface><span class=secno>4.8.1 </span>The <code>AbstractWorker</code> abstract interface</a></span></li>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="174a24e7617617691c1fea0de7a19411"><span class=en-original lang=en><a href=#dedicated-workers-and-the-worker-interface><span class=secno>4.8.2 </span>Dedicated workers and the <code>Worker</code> interface</a></span></li>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="4ffcaeb7e6840a21cd2cce4bda60ecdd"><span class=en-original lang=en><a href=#shared-workers-and-the-sharedworker-interface><span class=secno>4.8.3 </span>Shared workers and the <code>SharedWorker</code> interface</a></span></ol></ol></li>
 <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="a47f7c0f403c3aa899ecde08deff9a43"><span class=en-original lang=en><a href=#apis-available-to-workers><span class=secno>5 </span>APIs available to workers</a>
  </span><ol>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="37e9da5ea67ea86a29b62f8e0d1111ef"><span class=en-original lang=en><a href=#importing-scripts-and-libraries><span class=secno>5.1 </span>Importing scripts and libraries</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="91054561db04b2213a3534dc54ef2c3b"><span class=en-original lang=en><a href=#the-navigator-object><span class=secno>5.2 </span>The <code title=worker-Navigator>Navigator</code> object</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="7f0a8a7686a8cd5685cb93c1f3f82741"><span class=en-original lang=en><a href=#apis-defined-in-other-specifications><span class=secno>5.3 </span>APIs defined in other specifications</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="8dda0154835b8739bd1ada5c0b5c089f"><span class=en-original lang=en><a href=#interface-objects-and-constructors><span class=secno>5.4 </span>Interface objects and constructors</a></span></li>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="aae8cb440e8679d879f0df57ac164dc0"><span class=en-original lang=en><a href=#worker-locations><span class=secno>5.5 </span>Worker locations</a></span></ol></li>
 <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="721ff2a311123f40dbb5fe64d58f47d3"><span class=en-original lang=en><a class=no-num href=#references>References</a></span></li>
 <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="e3edbd0e5dae2337ce9018ac56f33463"><span class=en-original lang=en><a class=no-num href=#acknowledgements>Acknowledgements</a></span></ol>
<!--end-toc-->
  <hr><h2 id=introduction class="has-ja-translation" data-ja-hash="0b79795d3efc95b9976c7c5b933afce2"><span class=en-original lang=en><span class=secno>1 </span>Introduction</span><span class=ja-translation lang=ja><span class=secno>1 </span>はじめに</span></h2>

  <h3 id=scope class="has-ja-translation" data-ja-hash="5d113f2038d289f391614c39043629e8"><span class=en-original lang=en><span class=secno>1.1 </span>Scope</span><span class=ja-translation lang=ja><span class=secno>1.1 </span>適用範囲</span></h3>

  <p class="no-ja-translation" data-ja-hash="2b52ab89148ac538f9c9380fc5da5b2f"><span class=en-original lang=en><i>This section is non-normative.</i></span></p>

  <p class="no-ja-translation" data-ja-hash="2f78689edd39ccffc1a21b979c376f45"><span class=en-original lang=en>This specification defines an API for running scripts in the
  background independently of any user interface scripts.</span></p>

  <p class="no-ja-translation" data-ja-hash="f41b6868a33d2c4d265857efdf426694"><span class=en-original lang=en>This allows for long-running scripts that are not interrupted by
  scripts that respond to clicks or other user interactions, and
  allows long tasks to be executed without yielding to keep the page
  responsive.</span></p>

  <p class="no-ja-translation" data-ja-hash="52e3c8127ee80a92ae3709986b8f2450"><span class=en-original lang=en>Workers (as these background scripts are called herein) are
  relatively heavy-weight, and are not intended to be used in large
  numbers. For example, it would be inappropriate to launch one worker
  for each pixel of a four megapixel image. The examples below show
  some appropriate uses of workers.</span></p>

  <p class="no-ja-translation" data-ja-hash="497e60abbf38e141b92f7017f71dc302"><span class=en-original lang=en>Generally, workers are expected to be long-lived, have a high
  start-up performance cost, and a high per-instance memory cost.</span></p>


  <h3 id=tutorial class="has-ja-translation" data-ja-hash="368fe771261fcb18f7988833c9294a20"><span class=en-original lang=en><span class=secno>1.2 </span>Tutorial</span><span class=ja-translation lang=ja><span class=secno>1.2 </span>解説</span></h3>

  <p class="no-ja-translation" data-ja-hash="2b52ab89148ac538f9c9380fc5da5b2f"><span class=en-original lang=en><i>This section is non-normative.</i></span></p>

  <p class="has-ja-translation" data-ja-hash="c98bec741e84294c9feae0d581f897b6"><span class=en-original lang=en>There are a variety of uses that workers can be put to. The
  following subsections show various examples of this use.</span><span class=ja-translation lang=ja>労働者は色々なことに使えます。次の各節では、色々な使い方の例を示します。</span></p>

  <h4 id=a-background-number-crunching-worker class="has-ja-translation" data-ja-hash="03100d1ee403be709f47c37e6b55c758"><span class=en-original lang=en><span class=secno>1.2.1 </span>A background number-crunching worker</span><span class=ja-translation lang=ja><span class=secno>1.2.1 </span>数値処理背景労働者</span></h4>

  <p class="no-ja-translation" data-ja-hash="2b52ab89148ac538f9c9380fc5da5b2f"><span class=en-original lang=en><i>This section is non-normative.</i></span></p>

  <p class="has-ja-translation" data-ja-hash="6656ef1c2fd445878e165388d704a723"><span class=en-original lang=en>The simplest use of workers is for performing a computationally
  expensive task without interrupting the user interface.</span><span class=ja-translation lang=ja>労働者の一番単純な用法は、計算的に高価な仕事を利用者界面を中断させずに実行するというものです。</span></p>

  <p class="has-ja-translation" data-ja-hash="14941a1ddb566828a9181bcecf3a815a"><span class=en-original lang=en>In this example, the main document spawns a worker to
  (na&iuml;vely) compute prime numbers, and progressively displays the
  most recently found prime number.</span><span class=ja-translation lang=ja>この例では、主たる文書が労働者を作って素数を (素朴な方法で) 計算させ、
新しく見つかった素数を順番に表示してゆきます。</span></p>

  <p class="has-ja-translation" data-ja-hash="97bcf42c4070cbcef605cfa277d832fb"><span class=en-original lang=en>The main page is as follows:</span><span class=ja-translation lang=ja>主たる頁は次の通りです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="45b861d46157f155d38040db723bafd1"><span class=en-original lang=en>&lt;!DOCTYPE HTML&gt;
&lt;html&gt;
 &lt;head&gt;
  &lt;title&gt;Worker example: One-core computation&lt;/title&gt;
 &lt;/head&gt;
 &lt;body&gt;
  &lt;p&gt;The highest prime number discovered so far is: &lt;output id="result"&gt;&lt;/output&gt;&lt;/p&gt;
  &lt;script&gt;
   var worker = new Worker('worker.js');
   worker.onmessage = function (event) {
     document.getElementById('result').textContent = event.data;
   };
  &lt;/script&gt;
 &lt;/body&gt;
&lt;/html&gt;</span></pre>

  <p class="no-ja-translation" data-ja-hash="64b5d9bd2853f85edab220de5a199787"><span class=en-original lang=en>The <code title=dom-Worker><a href=#dom-worker>Worker()</a></code> constructor call
  creates a worker and returns a <code><a href=#worker>Worker</a></code> object
  representing that worker, which is used to communicate with the
  worker. That object's <code title=handler-Worker-onmessage><a href=#handler-worker-onmessage>onmessage</a></code> event handler
  attribute allows the code to receive messages from the worker.</span></p>

  <p class="has-ja-translation" data-ja-hash="12a62a74d5156b6d85136f5fc41a4ee1"><span class=en-original lang=en>The worker itself is as follows:</span><span class=ja-translation lang=ja>労働者自体は次の通りです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="35390f08d92125ad461fd6bb5969cb0c"><span class=en-original lang=en>var n = 1;
search: while (true) {
  n += 1;
  for (var i = 2; i &lt;= Math.sqrt(n); i += 1)
    if (n % i == 0)
     continue search;
  // found a prime!
  postMessage(n);
}</span></pre>

  <p class="no-ja-translation" data-ja-hash="48faeab09946f0578b4b421f4cf0a5db"><span class=en-original lang=en>The bulk of this code is simply an unoptimized search for a prime
  number. To send a message back to the page, the <code title=dom-DedicatedWorkerGlobalScope-postMessage><a href=#dom-dedicatedworkerglobalscope-postmessage>postMessage()</a></code>
  method is used to post a message when a prime is found.</span></p>

  <p class="has-ja-translation" data-ja-hash="add583522732edb8aca6202c451ddb27" data-ja-real-hash="19ee793c62fc7bda7447ccda3a91b44e"><span class=en-original lang=en><a href=http://www.whatwg.org/demos/workers/primes/page.html>View this example online</a>.</span><span class=ja-translation lang=ja><a href=http://www.whatwg.org/demos/workers/primes/page.html>この例をオンラインで表示する</a>。</span></p>


  <h4 id=a-worker-for-updating-a-client-side-database class="has-ja-translation" data-ja-hash="be08cb921deb5e88f7dcb3edbd9f0274"><span class=en-original lang=en><span class=secno>1.2.2 </span>A worker for updating a client-side database</span><span class=ja-translation lang=ja><span class=secno>1.2.2 </span>クライアント側データベースの更新のための労働者</span></h4>

  <p class="no-ja-translation" data-ja-hash="2b52ab89148ac538f9c9380fc5da5b2f"><span class=en-original lang=en><i>This section is non-normative.</i></span></p>

  <p class="no-ja-translation" data-ja-hash="e8e4acfb27dabd6fd72aa5a4af7b7d25"><span class=en-original lang=en>In this example, the main document spawns a worker whose only
  task is to listen for notifications from the server, and, when
  appropriate, either add or remove data from the client-side
  database.</span></p>

  <p class="has-ja-translation" data-ja-hash="88e890f11b614dc40f4d2453a66ec94f"><span class=en-original lang=en>Since no communication occurs between the worker and the main
  page, the main page can start the worker by just doing:</span><span class=ja-translation lang=ja>労働者と主たる頁の間に通信は発生しませんので、
主たる頁は単に次のようにするだけで労働者を開始できます。</span></p>

  <pre class="no-ja-translation" data-ja-hash="c87d2a32789642a7a7353364dffa7c04"><span class=en-original lang=en>&lt;script&gt;
 new Worker('worker.js');
&lt;/script&gt;</span></pre>

  <p class="has-ja-translation" data-ja-hash="12a62a74d5156b6d85136f5fc41a4ee1"><span class=en-original lang=en>The worker itself is as follows:</span><span class=ja-translation lang=ja>労働者自体は次の通りです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="cfd35229b68e597b6a21322a3e3c1aea"><span class=en-original lang=en>var server = new WebSocket('ws://whatwg.org/database');
var database = openDatabase('demobase', '1.0', 'Demo Database', 10240);
server.onmessage = function (event) {
  // data is in the format "command key value"
  var data = event.data.split(' ');
  switch (data[0]) {
    case '+':
     database.transaction(function(tx) {
       tx.executeSql('INSERT INTO pairs (key, value) VALUES (?, ?)', data[1], data[2]);
     });
    case '-':
     database.transaction(function(tx) {
       tx.executeSql('DELETE FROM pairs WHERE key=? AND value=?', data[1], data[2]);
     });
  }
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="df7990f8fb4ac6850b65c14c08446f5c"><span class=en-original lang=en>This connects to the server using the <code>WebSocket</code>
  mechanism and opens the local database (which, we presume, has been
  created earlier). The worker then just listens for messages from the
  server and acts on them as appropriate, forever (or until the main
  page is closed).</span></p>

  <p class="no-ja-translation" data-ja-hash="f0d091179997558acbbf256bd7379b3d"><span class=en-original lang=en><a href=http://www.whatwg.org/demos/workers/database-updater/page.html>View
  this example online</a>. (This example will not actually function,
  since the server does not actually exist and the database is not
  created by this sample code.)</span></p>


  <h4 id=worker-used-for-background-i/o class="no-ja-translation" data-ja-hash="26a2e24494eb4f94591467b79f68f6f2"><span class=en-original lang=en><span class=secno>1.2.3 </span>Worker used for background I/O</span></h4>

  <p class="no-ja-translation" data-ja-hash="2b52ab89148ac538f9c9380fc5da5b2f"><span class=en-original lang=en><i>This section is non-normative.</i></span></p>

  <p class="has-ja-translation" data-ja-hash="eb288220a303d56acd4e151bca42fe6e"><span class=en-original lang=en>In this example, the main document uses two workers, one for
  fetching stock updates for at regular intervals, and one for
  fetching performing search queries that the user requests.</span><span class=ja-translation lang=ja>この例では、主たる文書は2つの労働者を使います。
1つは一定間隔で株価の更新を取得するためのもので、もう1つは利用者の要求した検索の照会を行う取得のためのものです。</span></p>

  <p class="has-ja-translation" data-ja-hash="97bcf42c4070cbcef605cfa277d832fb"><span class=en-original lang=en>The main page is as follows:</span><span class=ja-translation lang=ja>主たる頁は次の通りです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="a4e743797f3cad5ba0d0016878e0e28c"><span class=en-original lang=en>&lt;!DOCTYPE HTML&gt;
&lt;html&gt;
 &lt;head&gt;
  &lt;title&gt;Worker example: Stock ticker&lt;/title&gt;
  &lt;script&gt;
   // TICKER
   var symbol = 'GOOG'; // default symbol to watch
   var ticker = new Worker('ticker.js');

   // SEARCHER
   var searcher = new Worker('searcher.js');
   function search(query) {
     searcher.postMessage(query);
   }

   // SYMBOL SELECTION UI
   function select(newSymbol) {
     symbol = newSymbol;
     ticker.postMessage(symbol);
   }
  &lt;/script&gt;
 &lt;/head&gt;
 &lt;body onload="search('')"&gt;
  &lt;p&gt;&lt;output id="symbol"&gt;&lt;/output&gt; &lt;output id="value"&gt;&lt;/output&gt;&lt;/p&gt;
  &lt;script&gt;
   ticker.onmessage = function (event) {
     var data = event.data.split(' ');
     document.getElementById('symbol').textContent = data[0];
     document.getElementById('value').textContent = data[1];
   };
   ticker.postMessage(symbol);
  &lt;/script&gt;
  &lt;p&gt;&lt;label&gt;Search: &lt;input type="text" autofocus oninput="search(this.value)"&gt;&lt;/label&gt;&lt;/p&gt;
  &lt;ul id="results"&gt;&lt;/ul&gt;
  &lt;script&gt;
   searcher.onmessage = function (event) {
     var data = event.data.split(' ');
     var results = document.getElementById('results');
     while (results.hasChildNodes()) // clear previous results
       results.removeChild(results.firstChild);
     for (var i = 0; i &lt; data.length; i += 1) {
       // add a list item with a button for each result
       var li = document.createElement('li');
       var button = document.createElement('button');
       button.value = data[i];
       button.type = 'button';
       button.onclick = function () { select(this.value); };
       button.textContent = data[i];
       li.appendChild(button);
       results.appendChild(li);
     }
   };
  &lt;/script&gt;
  &lt;p&gt;(The data in this example is not real. Try searching for "Google" or "Apple".)&lt;/p&gt;
 &lt;/body&gt;
&lt;/html&gt;</span></pre>

  <p class="has-ja-translation" data-ja-hash="4cc7e781e44db82f8bd32020954bb94a"><span class=en-original lang=en>The two workers use a common library for performing the actual
  network calls. This library is as follows:</span><span class=ja-translation lang=ja>両労働者は実際のネットワークの呼び出しを行う共通のライブラリーを使います。
このライブラリーは次の通りです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="764d750a19834bf904d276466724339c"><span class=en-original lang=en>function get(url) {
  try {
    var xhr = new XMLHttpRequest();
    xhr.open('GET', url, false);
    xhr.send();
    return xhr.responseText;
  } catch (e) {
    return ''; // turn all errors into empty results
  }
}</span></pre>

  <p class="has-ja-translation" data-ja-hash="ee10423864c33d68e8676bf88cb75046"><span class=en-original lang=en>The stock updater worker is as follows:</span><span class=ja-translation lang=ja>株価更新者の労働者は次の通りです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="66ef47eaf421ea8066871b71807859be"><span class=en-original lang=en>importScripts('io.js');
var timer;
var symbol;
function update() {
  postMessage(symbol + ' ' + get('stock.cgi?' + symbol));
  timer = setTimeout(update, 10000);
}
onmessage = function (event) {
  if (timer)
    clearTimeout(timer);
  symbol = event.data;
  update();
};</span></pre>

  <p class="has-ja-translation" data-ja-hash="aa6a78ceb7b91cdf90925cc36c6c6676"><span class=en-original lang=en>The search query worker is as follows:</span><span class=ja-translation lang=ja>検索の照会の労働者は次の通りです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="ac0353e2a69ae5ffdc861cca404ef9f0"><span class=en-original lang=en>importScripts('io.js');
onmessage = function (event) {
  postMessage(get('search.cgi?' + event.data));
};</span></pre>

  <p class="has-ja-translation" data-ja-hash="add583522732edb8aca6202c451ddb27" data-ja-real-hash="5855651f68b535b77cb2b82bed593472"><span class=en-original lang=en><a href=http://www.whatwg.org/demos/workers/stocks/page.html>View this example online</a>.</span><span class=ja-translation lang=ja><a href=http://www.whatwg.org/demos/workers/stocks/page.html>この例をオンラインで表示する</a>。</span></p>


  <h4 id=shared-workers class="has-ja-translation" data-ja-hash="634755c2f50b08b49a82f30428b1a961"><span class=en-original lang=en><span class=secno>1.2.4 </span>Shared workers</span><span class=ja-translation lang=ja><span class=secno>1.2.4 </span>共有労働者</span></h4>

  <p class="no-ja-translation" data-ja-hash="2b52ab89148ac538f9c9380fc5da5b2f"><span class=en-original lang=en><i>This section is non-normative.</i></span></p>

  <p class="no-ja-translation" data-ja-hash="2ec2b66f1e8130c8e0552d348a633841"><span class=en-original lang=en>In this example, multiple windows (viewers) can be opened that
  are all viewing the same map. All the windows share the same map
  information, with a single worker coordinating all the viewers. Each
  viewer can move around independently, but if they set any data on
  the map, all the viewers are updated.</span></p>

  <p class="has-ja-translation" data-ja-hash="2bf6969d7d27e56c707ae9970fdd476f"><span class=en-original lang=en>The main page isn't interesting, it merely provides a way to open
  the viewers:</span><span class=ja-translation lang=ja>主たる頁は特に何もなく、単に表示器を開くためだけのものです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="e27ef9096d7661be60af654b55813524"><span class=en-original lang=en>&lt;!DOCTYPE HTML&gt;
&lt;html&gt;
 &lt;head&gt;
  &lt;title&gt;Workers example: Multiviewer&lt;/title&gt;
  &lt;script&gt;
   function openViewer() {
     window.open('viewer.html');
   }
  &lt;/script&gt;
 &lt;/head&gt;
 &lt;body&gt;
  &lt;p&gt;&lt;button type=button onclick="openViewer()"&gt;Open a new
  viewer&lt;/button&gt;&lt;/p&gt;
  &lt;p&gt;Each viewer opens in a new window. You can have as many viewers
  as you like, they all view the same data.&lt;/p&gt;
 &lt;/body&gt;
&lt;/html&gt;</span></pre>

  <p class="has-ja-translation" data-ja-hash="cee02afe1e87e7182f5219ccf54757ca"><span class=en-original lang=en>The viewer is more involved:</span><span class=ja-translation lang=ja>表示器はもっと色々しています。</span></p>

  <pre class="no-ja-translation" data-ja-hash="6f90bb09ab3ecf0dc089f72f0f7bf32b"><span class=en-original lang=en>&lt;!DOCTYPE HTML&gt;
&lt;html&gt;
 &lt;head&gt;
  &lt;title&gt;Workers example: Multiviewer viewer&lt;/title&gt;
  &lt;script&gt;
   var worker = new SharedWorker('worker.js', 'core');

   // CONFIGURATION
   function configure(event) {
     if (event.data.substr(0, 4) != 'cfg ') return;
     var name = event.data.substr(4).split(' ', 1);
     // update display to mention our name is name
     document.getElementsByTagName('h1')[0].textContent += ' ' + name;
     // no longer need this listener
     worker.port.removeEventListener('message', configure, false);
   }
   worker.port.addEventListener('message', configure, false);

   // MAP
   function paintMap(event) {
     if (event.data.substr(0, 4) != 'map ') return;
     var data = event.data.substr(4).split(',');
     // display tiles data[0] .. data[8]
     var canvas = document.getElementById('map');
     var context = canvas.getContext('2d');
     for (var y = 0; y &lt; 3; y += 1) {
       for (var x = 0; x &lt; 3; x += 1) {
         var tile = data[y * 3 + x];
         if (tile == '0')
           context.fillStyle = 'green';
         else 
           context.fillStyle = 'maroon';
         fillRect(x * 50, y * 50, 50, 50);
       }
     }
   }
   worker.port.addEventListener('message', paintMap, false);

   // PUBLIC CHAT
   function updatePublicChat(event) {
     if (event.data.substr(0, 4) != 'txt ') return;
     var name = event.data.substr(4).split(' ', 1);
     var message = event.data.substr(4 + length(name) + 1);
     // display "&lt;name&gt; message" in public chat
     var dialog = document.getElementById('public');
     var dt = document.createElement('dt');
     dt.textContent = name;
     dialog.appendChild(dt);
     var dd = document.createElement('dd');
     dd.textContent = message;
     dialog.appendChild(dd);
   }
   worker.port.addEventListener('message', updatePublicChat, false);

   // PRIVATE CHAT
   function startPrivateChat(event) {
     if (event.data.substr(0, 4) != 'msg ') return;
     var name = event.data.substr(4).split(' ', 1);
     var port = event.ports[0];
     // display a private chat UI
     var ul = document.getElementById('private');
     var li = document.createElement('li');
     var h3 = document.createElement('h3');
     h3.textContent = 'Private chat with ' + name;
     li.appendChild(h3);
     var dialog = document.createElement('dialog');
     var addMessage = function(name, message) {
       var dt = document.createElement('dt');
       dt.textContent = name;
       dialog.appendChild(dt);
       var dd = document.createElement('dd');
       dd.textContent = message;
       dialog.appendChild(dd);
     };
     port.onmessage = function (event) {
       addMessage(name, event.data);
     };
     li.appendChild(dialog);
     var form = document.createElement('form');
     var p = document.createElement('p');
     var input = document.createElement('input');
     input.size = 50;
     p.appendChild(input);
     p.appendChild(document.createTextNode(' '));
     var button = document.createElement('button');
     button.textContent = 'Post';
     p.appendChild(button);
     form.onsubmit = function () {
       port.postMessage(input.value);
       addMessage('me', input.value);
       input.value = '';
       return false;
     };
     form.appendChild(p);
     li.appendChild(form);
   }
   worker.port.addEventListener('message', startPrivateChat, false);
  &lt;/script&gt;
 &lt;/head&gt;
 &lt;body&gt;
  &lt;h1&gt;Viewer&lt;/h1&gt;
  &lt;h2&gt;Map&lt;/h2&gt;
  &lt;p&gt;&lt;canvas id="map" height=150 width=150&gt;&lt;/canvas&gt;&lt;/p&gt;
  &lt;p&gt;
   &lt;button type=button onclick="worker.port.postMessage('mov left')"&gt;Left&lt;/button&gt;
   &lt;button type=button onclick="worker.port.postMessage('mov up')"&gt;Up&lt;/button&gt;
   &lt;button type=button onclick="worker.port.postMessage('mov down')"&gt;Down&lt;/button&gt;
   &lt;button type=button onclick="worker.port.postMessage('mov right')"&gt;Right&lt;/button&gt;
   &lt;button type=button onclick="worker.port.postMessage('set 0')"&gt;Set 0&lt;/button&gt;
   &lt;button type=button onclick="worker.port.postMessage('set 1')"&gt;Set 1&lt;/button&gt;
  &lt;/p&gt;
  &lt;h2&gt;Public Chat&lt;/h2&gt;
  &lt;dialog id="public"&gt;&lt;/dialog&gt;
  &lt;form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;"&gt;
   &lt;p&gt;
    &lt;input type="text" name="message" size="50"&gt;
    &lt;button&gt;Post&lt;/button&gt;
   &lt;/p&gt;
  &lt;/form&gt;
  &lt;h2&gt;Private Chat&lt;/h2&gt;
  &lt;ul id="private"&gt;&lt;/ul&gt;
 &lt;/body&gt;
&lt;/html&gt;
</span></pre>

  <p class="has-ja-translation" data-ja-hash="397850dab731150b72d5f0276dab0081"><span class=en-original lang=en>There are several key things worth noting about the way the
  viewer is written.</span><span class=ja-translation lang=ja>表示器の書き方についていくつか注意したい重要な点があります。</span></p>

  <p class="has-ja-translation" data-ja-hash="8bc9c1f9e0e102128838ea8c31c51306"><span class=en-original lang=en><strong>Multiple listeners</strong>. Instead of a single message
  processing function, the code here attaches multiple event
  listeners, each one performing a quick check to see if it is
  relevant for the message. In this example it doesn't make much
  difference, but if multiple authors wanted to collaborate using a
  single port to communicate with a worker, it would allow for
  independent code instead of changes having to all be made to a
  single event handling function.</span><span class=ja-translation lang=ja><strong>複数の聴取器</strong>。この符号では、メッセージ処理関数を1つ用意する代わりに、
複数の事象聴取器を付与し、それぞれが、それがメッセージに関連するかどうかを見るためにさらりと検査を行っています。
この例では大きな違いにはなりませんが、複数の著者が労働者と通信するために1つのポートを使って協調したい場合には、
独立した符号にできるので変更がある度に1つの事象取扱関数をいじらざるを得なくて済みます。</span></p>

  <p class="no-ja-translation" data-ja-hash="ce2f17c1c25589a0d4507c6fa9c1f532"><span class=en-original lang=en>Registering event listeners in this way also allows you to
  unregister specific listeners when you are done with them, as is
  done with the <code title="">configure()</code> method in this
  example.</span></p>

  <p class="has-ja-translation" data-ja-hash="4eb1fa2095f65662225da4c52db274f1"><span class=en-original lang=en>Finally, the worker:</span><span class=ja-translation lang=ja>最後に、労働者は次のようになります。</span></p>

  <pre class="no-ja-translation" data-ja-hash="2a6833ffcfe9252a21a8582ad69a4adf"><span class=en-original lang=en>
var nextName = 0;
function getNextName() {
  // this could use more friendly names
  // but for now just return a number
  return nextName++;
}

var map = [
 [0, 0, 0, 0, 0, 0, 0],
 [1, 1, 0, 1, 0, 1, 1],
 [0, 1, 0, 1, 0, 0, 0],
 [0, 1, 0, 1, 0, 1, 1],
 [0, 0, 0, 1, 0, 0, 0],
 [1, 0, 0, 1, 1, 1, 1],
 [1, 1, 0, 1, 1, 0, 1],
];

function wrapX(x) {
  if (x &lt; 0) return wrapX(x + map[0].length);
  if (x &gt;= map[0].length) return wrapX(x - map[0].length);
  return x;
}

function wrapY(y) {
  if (y &lt; 0) return wrapY(y + map.length);
  if (y &gt;= map[0].length) return wrapY(y - map.length);
  return y;
}

function sendMapData(callback) {
  var data = '';
  for (var y = viewer.y-1; y &lt;= viewer.y+1; y += 1) {
    for (var x = viewer.x-1; x &lt;= viewer.x+1; x += 1) {
      if (data != '')
        data += ',';
      data += map[y][x];
    }
  }
  callback('map ' + data);
}

var viewers = {};
onconnect = function (event) {
  event.ports[0]._name = getNextName();
  event.ports[0]._data = { port: event.port, x: 0, y: 0, };
  viewers[event.ports[0]._name] = event.port._data;
  event.ports[0].postMessage('cfg ' + name);
  event.ports[0].onmessage = getMessage;
  sendMapData(event.ports[0].postMessage);
};

function getMessage(event) {
  switch (event.data.substr(0, 4)) {
    case 'mov ':
      var direction = event.data.substr(4);
      var dx = 0;
      var dy = 0;
      switch (direction) {
        case 'up': dy = -1; break;
        case 'down': dy = 1; break;
        case 'left': dx = -1; break;
        case 'right': dx = 1; break;
      }
      event.target._data.x = wrapX(event.target._data.x + dx);
      event.target._data.y = wrapY(event.target._data.y + dy);
      sendMapData(event.target.postMessage);
      break;
    case 'set ':
      var value = event.data.substr(4);
      map[event.target._data.y][event.target._data.x] = value;
      for (var viewer in viewers)
        sendMapData(viewers[viewer].port.postMessage);
      break;
    case 'txt ':
      var name = event.target._name;
      var message = event.data.substr(4);
      for (var viewer in viewers)
        viewers[viewer].port.postMessage('txt ' + name + ' ' + message);
      break;
    case 'msg ':
      var party1 = event._data;
      var party2 = viewers[event.data.substr(4).split(' ', 1)];
      if (party2) {
        var channel = new MessageChannel();
        party1.port.postMessage('msg ' + party2.name, [channel.port1]);
        party2.port.postMessage('msg ' + party1.name, [channel.port2]);
      }
      break;
  }
}</span></pre>

  <p class="no-ja-translation" data-ja-hash="80f59a8dae1df6b25c537e5041683f5d"><span class=en-original lang=en><strong>Connecting to multiple pages</strong>. The script uses
  the <code title=handler-SharedWorkerGlobalScope-onconnect><a href=#handler-sharedworkerglobalscope-onconnect>onconnect</a></code>
  event listener to listen for multiple connections.</span></p>

  <p class="has-ja-translation" data-ja-hash="5ce666b6338718b46fb0dee22dbea88c"><span class=en-original lang=en><strong>Direct channels</strong>. When the worker receives a
  "msg" message from one viewer naming another viewer, it sets up a
  direct connection between the two, so that the two viewers can
  communicate directly without the worker having to proxy all the
  messages.</span><span class=ja-translation lang=ja><strong>直接通信路</strong>。労働者がある閲覧器から他の閲覧器を名指した「msg」メッセージを受信した時は、
両者間の直接の接続を設定し、労働者がすべてのメッセージを仲介せずとも両閲覧器が直接通信できるようにします。</span></p>

  <p class="has-ja-translation" data-ja-hash="add583522732edb8aca6202c451ddb27" data-ja-real-hash="8d892cfe0423f9a15e275e47c6b45600"><span class=en-original lang=en><a href=http://www.whatwg.org/demos/workers/multiviewer/page.html>View this example online</a>.</span><span class=ja-translation lang=ja><a href=http://www.whatwg.org/demos/workers/multiviewer/page.html>この例をオンラインで表示する</a>。</span></p>


  <h4 id=delegation class="has-ja-translation" data-ja-hash="57b11d3816e9f83adb4dd2ecb2a311b5"><span class=en-original lang=en><span class=secno>1.2.5 </span>Delegation</span><span class=ja-translation lang=ja><span class=secno>1.2.5 </span>委譲</span></h4>

  <p class="no-ja-translation" data-ja-hash="2b52ab89148ac538f9c9380fc5da5b2f"><span class=en-original lang=en><i>This section is non-normative.</i></span></p>

  <p class="no-ja-translation" data-ja-hash="318b797bf0c9a2cdaa476f36993911b4"><span class=en-original lang=en>With multicore CPUs becoming prevalent, one way to obtain better
  performance is to split computationally expensive tasks amongst
  multiple workers. In this example, a computationally expensive task
  that is to be performed for every number from 1 to 10,000,000 is
  farmed out to ten subworkers.</span></p>

  <p class="has-ja-translation" data-ja-hash="c5074121435848ef6ad420f030cb5060"><span class=en-original lang=en>The main page is as follows, it just reports the result:</span><span class=ja-translation lang=ja>主たる頁は次の通りで、単に結果を報告するだけです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="45b861d46157f155d38040db723bafd1"><span class=en-original lang=en>&lt;!DOCTYPE HTML&gt;
&lt;html&gt;
 &lt;head&gt;
  &lt;title&gt;Worker example: One-core computation&lt;/title&gt;
 &lt;/head&gt;
 &lt;body&gt;
  &lt;p&gt;The highest prime number discovered so far is: &lt;output id="result"&gt;&lt;/output&gt;&lt;/p&gt;
  &lt;script&gt;
   var worker = new Worker('worker.js');
   worker.onmessage = function (event) {
     document.getElementById('result').textContent = event.data;
   };
  &lt;/script&gt;
 &lt;/body&gt;
&lt;/html&gt;</span></pre>

  <p class="has-ja-translation" data-ja-hash="12a62a74d5156b6d85136f5fc41a4ee1"><span class=en-original lang=en>The worker itself is as follows:</span><span class=ja-translation lang=ja>労働者自体は次の通りです。</span></p>

  <pre class="no-ja-translation" data-ja-hash="c2f14df3c3648ecb143c9e271b6721df"><span class=en-original lang=en>// settings
var num_workers = 10;
var items_per_worker = 1000000;

// start the workers
var result = 0;
var pending_workers = num_workers;
for (var i = 0; i &lt; num_workers; i += 1) {
  var worker = new Worker('core.js');
  worker.postMessage(i * items_per_worker);
  worker.postMessage((i+1) * items_per_worker);
  worker.onmessage = storeResult;
}

// handle the results
function storeResult(event) {
  result += 1*event.data;
  pending_workers -= 1;
  if (pending_workers &lt;= 0)
    postMessage(result); // finished!
}</span></pre>

  <p class="has-ja-translation" data-ja-hash="f9236b42d2a99d988b848353511797fc"><span class=en-original lang=en>It consists of a loop to start the subworkers, and then a handler
  that waits for all the subworkers to respond.</span><span class=ja-translation lang=ja>これは部分労働者を開始するループと、
すべての部分労働者が応答するのを待つ取扱器から成っています。</span></p>

  <p class="has-ja-translation" data-ja-hash="53f3483f6fffa25f7c6963e58d683f43"><span class=en-original lang=en>The subworkers are implemented as follows:</span><span class=ja-translation lang=ja>部分労働者は次のように実装します。</span></p>

  <pre class="no-ja-translation" data-ja-hash="90fc569c1c634a87b725ebbe4cc1e2f4"><span class=en-original lang=en>var start;
onmessage = getStart;
function getStart(event) {
  start = 1*event.data;
  onmessage = getEnd;
}

var end;
function getEnd(event) {
  end = 1*event.data;
  onmessage = null;
  work();
}

function work() {
  var result = 0;
  for (var i = start; i &lt; end; i += 1) {
    // perform some complex calculation here
    result += 1;
  }
  postMessage(result);
  close();
}</span></pre>

  <p class="has-ja-translation" data-ja-hash="fbf1b083b03c85854a8e892ef8add172"><span class=en-original lang=en>They receive two numbers in two events, perform the computation
  for the range of numbers thus specified, and then report the result
  back to the parent.</span><span class=ja-translation lang=ja>部分労働者は2つの事象で2つの数を受信し、指定された数の範囲の計算を行った後、
結果を親に報告します。
</span></p>

  <p class="has-ja-translation" data-ja-hash="add583522732edb8aca6202c451ddb27" data-ja-real-hash="4318fb9a581a7c14e58bfb2d61809f0c"><span class=en-original lang=en><a href=http://www.whatwg.org/demos/workers/multicore/page.html>View this example online</a>.</span><span class=ja-translation lang=ja><a href=http://www.whatwg.org/demos/workers/multicore/page.html>この例をオンラインで表示する</a>。</span></p>


  <h4 id=providing-libraries class="has-ja-translation" data-ja-hash="6c37218e175bff77f69bd84b1ab5da58"><span class=en-original lang=en><span class=secno>1.2.6 </span>Providing libraries</span><span class=ja-translation lang=ja><span class=secno>1.2.6 </span>ライブラリーの提供</span></h4>

  <p class="no-ja-translation" data-ja-hash="2b52ab89148ac538f9c9380fc5da5b2f"><span class=en-original lang=en><i>This section is non-normative.</i></span></p>

  <p class="no-ja-translation" data-ja-hash="12371907fb7e8389f76fabaf7a5f8303"><span class=en-original lang=en>Suppose that a cryptography library is made available that
  provides three tasks:</span></p>

  <dl><dt class="has-ja-translation" data-ja-hash="6ea027035e660e254aba77f4bd9cb6e7"><span class=en-original lang=en>Generate a public/private key pair</span><span class=ja-translation lang=ja>公開鍵・秘密鍵の組の生成</span></dt>

   <dd class="no-ja-translation" data-ja-hash="cf9020803baa896d8a183fe324563704"><span class=en-original lang=en>Takes a port, on which it will send two messages, first the
   public key and then the private key.</span></dd>

   <dt class="no-ja-translation" data-ja-hash="fb7dd035a8141087578088ce61f9db22"><span class=en-original lang=en>Given a plaintext and a public key, return the corresponding cyphertext</span></dt>

   <dd class="no-ja-translation" data-ja-hash="1d31efc883e22a218f807161c65291f0"><span class=en-original lang=en>Takes a port, to which any number of messages can be sent, the
   first giving the public key, and the remainder giving the
   plaintext, each of which is encrypted and then sent on that same
   channel as the cyphertext. The user can close the port when it is
   done encrypting content.</span></dd>

   <dt class="no-ja-translation" data-ja-hash="11ea02c6f203744166e5a89e81a81337"><span class=en-original lang=en>Given a cyphertext and a private key, return the corresponding plaintext</span></dt>

   <dd class="no-ja-translation" data-ja-hash="c157fe0e540c248dc1db29edbd80ff82"><span class=en-original lang=en>Takes a port, to which any number of messages can be sent, the
   first giving the private key, and the remainder giving the
   cyphertext, each of which is decrypted and then sent on that same
   channel as the plaintext. The user can close the port when it is
   done decrypting content.</span></dd>

  </dl><p class="has-ja-translation" data-ja-hash="0e39ac88e71e60206c341926e3785dcd"><span class=en-original lang=en>The library itself is as follows:</span><span class=ja-translation lang=ja>ライブラリー自体は次のようになります。</span></p>

  <pre class="no-ja-translation" data-ja-hash="6c23fb6fef8f715101d908de56f2cb63"><span class=en-original lang=en>function handleMessage(e) {
  if (e.data == "genkeys")
    genkeys(e.ports[0]);
  else if (e.data == "encrypt")
    encrypt(e.ports[0]);
  else if (e.data == "decrypt")
    decrypt(e.ports[0]);
}

function genkeys(p) {
  var keys = _generateKeyPair();
  p.postMessage(keys[0]);
  p.postMessage(keys[1]);
}

function encrypt(p) {
  var key, state = 0;
  p.onmessage = function (e) {
    if (state == 0) {
      key = e.data;
      state = 1;
    } else {
      p.postMessage(_encrypt(key, e.data));
    }
  };
}

function decrypt(p) {
  var key, state = 0;
  p.onmessage = function (e) {
    if (state == 0) {
      key = e.data;
      state = 1;
    } else {
      p.postMessage(_decrypt(key, e.data));
    }
  };
}

// support being used as a shared worker as well as a dedicated worker
if (this.onmessage) // dedicated worker
  onmessage = handleMessage;
else // shared worker
  onconnect = function (e) { e.port.onmessage = handleMessage; }


// the "crypto" functions:

function _generateKeyPair() {
  return [Math.random(), Math.random()];
}

function _encrypt(k, s) {
  return 'encrypted-' + k + ' ' + s;
}

function _decrypt(k, s) {
  return s.substr(s.indexOf(' ')+1);
}</span></pre>

  <p class="no-ja-translation" data-ja-hash="e6e3003b829ed060f5926d1763f29c2e"><span class=en-original lang=en>Note that the crypto functions here are just stubs and don't do
  real cryptography.</span></p>

  <p class="has-ja-translation" data-ja-hash="76f1d5866d92bc1036d1198cf4eda428"><span class=en-original lang=en>This library could be used as follows:</span><span class=ja-translation lang=ja>このライブラリーは次のように使うことができます。</span></p>

  <pre class="no-ja-translation" data-ja-hash="e88a411ca9b20f088116732dc0db6171"><span class=en-original lang=en>&lt;!DOCTYPE HTML&gt;
&lt;html&gt;
 &lt;head&gt;
  &lt;title&gt;Worker example: Crypto library&lt;/title&gt;
  &lt;script&gt;
   var crytoLib = new Worker('libcrypto-v1.js'); // or could use 'libcrypto-v2.js'
   function getKeys() {
     var state = 0;
     cryptoLib.startConversation("genkeys").onmessage = function (e) {
       if (state == 0)
         document.getElementById('public').value = e.data;
       else if (state == 1)
         document.getElementById('private').value = e.data;
       state += 1;
     };
   }
   function enc() {
     var port = cryptoLib.startConversation("encrypt");
     port.postMessage(document.getElementById('public').value);
     port.postMessage(document.getElementById('input').value);
     port.onmessage = function (e) {
       document.getElementById('input').value = e.data;
       port.close();
     };
   }
   function dec() {
     var port = cryptoLib.startConversation("decrypt");
     port.postMessage(document.getElementById('private').value);
     port.postMessage(document.getElementById('input').value);
     port.onmessage = function (e) {
       document.getElementById('input').value = e.data;
       port.close();
     };
   }
  &lt;/script&gt;
  &lt;style&gt;
   textarea { display: block; }
  &lt;/style&gt;
 &lt;/head&gt;
 &lt;body onload="getKeys()"&gt;
  &lt;fieldset&gt;
   &lt;legend&gt;Keys&lt;/legend&gt;
   &lt;p&gt;&lt;label&gt;Public Key: &lt;textarea id="public"&gt;&lt;/textarea&gt;&lt;/label&gt;&lt;/p&gt;
   &lt;p&gt;&lt;label&gt;Private Key: &lt;textarea id="private"&gt;&lt;/textarea&gt;&lt;/label&gt;&lt;/p&gt;
  &lt;/fieldset&gt;
  &lt;p&gt;&lt;label&gt;Input: &lt;textarea id="input"&gt;&lt;/textarea&gt;&lt;/label&gt;&lt;/p&gt;
  &lt;p&gt;&lt;button onclick="enc()"&gt;Encrypt&lt;/button&gt; &lt;button onclick="dec()"&gt;Decrypt&lt;/button&gt;&lt;/p&gt;
 &lt;/body&gt;
&lt;/html&gt;</span></pre>

  <p class="no-ja-translation" data-ja-hash="13181de825fa0e152c5a954e55715a15"><span class=en-original lang=en>A later version of the API, though, might want to offload all the
  crypto work onto subworkers. This could be done as follows:</span></p>

  <pre class="no-ja-translation" data-ja-hash="4700bd96e4f3524347953c148b483479"><span class=en-original lang=en>function handleMessage(e) {
  if (e.data == "genkeys")
    genkeys(e.ports[0]);
  else if (e.data == "encrypt")
    encrypt(e.ports[0]);
  else if (e.data == "decrypt")
    decrypt(e.ports[0]);
}

function genkeys(p) {
  var generator = new Worker('libcrypto-v2-generator.js');
  generator.postMessage('', [p]);
}

function encrypt(p) {
  p.onmessage = function (e) {
    var key = e.data;
    var encryptor = new Worker('libcrypto-v2-encryptor.js');
    encryptor.postMessage(key, [p]);
  };
}

function encrypt(p) {
  p.onmessage = function (e) {
    var key = e.data;
    var decryptor = new Worker('libcrypto-v2-decryptor.js');
    decryptor.postMessage(key, [p]);
  };
}

// support being used as a shared worker as well as a dedicated worker
if (this.onmessage) // dedicated worker
  onmessage = handleMessage;
else // shared worker
  onconnect = function (e) { e.ports[0].onmessage = handleMessage };
</span></pre>

  <p class="has-ja-translation" data-ja-hash="fc1d14c413a94a9015153067739845e7"><span class=en-original lang=en>The little subworkers would then be as follows.</span><span class=ja-translation lang=ja>小部分労働者は次の通りです。</span></p>

  <p class="has-ja-translation" data-ja-hash="66f9c4d246b0081919ced7e46c4a9db2"><span class=en-original lang=en>For generating key pairs:</span><span class=ja-translation lang=ja>鍵組の生成用:</span></p>

  <pre class="no-ja-translation" data-ja-hash="7fcbde64ee437c101414bcc98d9e1ee0"><span class=en-original lang=en>onmessage = function (e) {
  var k = _generateKeyPair();
  e.ports[0].postMessage(k[0]);
  e.ports[0].postMessage(k[1]);
  close();
}

function _generateKeyPair() {
  return [Math.random(), Math.random()];
}</span></pre>

  <p class="has-ja-translation" data-ja-hash="1f07f24df05f20de47483db4dfde2017"><span class=en-original lang=en>For encrypting:</span><span class=ja-translation lang=ja>暗号化用:</span></p>

  <pre class="no-ja-translation" data-ja-hash="94aaf906f90e9b3539c4219ef2be60cf"><span class=en-original lang=en>onmessage = function (e) {
  var key = e.data;
  e.ports[0].onmessage = function (e) {
    var s = e.data;
    postMessage(_encrypt(key, s));
  }
}

function _encrypt(k, s) {
  return 'encrypted-' + k + ' ' + s;
}</span></pre>

  <p class="has-ja-translation" data-ja-hash="abf884f40593747f458e7d7400b1eb21"><span class=en-original lang=en>For decrypting:</span><span class=ja-translation lang=ja>解読用:</span></p>

  <pre class="no-ja-translation" data-ja-hash="c91e2f3055da293b534ac3c10648b23e"><span class=en-original lang=en>onmessage = function (e) {
  var key = e.data;
  e.ports[0].onmessage = function (e) {
    var s = e.data;
    postMessage(_decrypt(key, s));
  }
}

function _decrypt(k, s) {
  return s.substr(s.indexOf(' ')+1);
}</span></pre>

  <p class="no-ja-translation" data-ja-hash="c8da0ee0afd0a36dc51fa6bebbb8a3e9"><span class=en-original lang=en>Notice how the users of the API don't have to even know that this
  is happening &mdash; the API hasn't changed; the library can
  delegate to subworkers without changing its API, even though it is
  accepting data using message channels.</span></p>

  <p class="has-ja-translation" data-ja-hash="add583522732edb8aca6202c451ddb27" data-ja-real-hash="22a665d401474bea0ab24f5873ba4d61"><span class=en-original lang=en><a href=http://www.whatwg.org/demos/workers/crypto/page.html>View this example online</a>.</span><span class=ja-translation lang=ja><a href=http://www.whatwg.org/demos/workers/crypto/page.html>この例をオンラインで表示する</a>。</span></p>


  <h2 id=conformance-requirements class="has-ja-translation" data-ja-hash="05644f41fb2fbf61aaab52464b2edf3b"><span class=en-original lang=en><span class=secno>2 </span>Conformance requirements</span><span class=ja-translation lang=ja><span class=secno>2 </span>適合性要件</span></h2>

  <p class="has-ja-translation" data-ja-hash="8b0f72fe04577949924ab1e2997e0d8b"><span class=en-original lang=en>All diagrams, examples, and notes in this specification are
  non-normative, as are all sections explicitly marked non-normative.
  Everything else in this specification is normative.</span><span class=ja-translation lang=ja>この仕様書のすべての図、例示、注意書き、ならびに規定の一部ではないと明記したすべての節は、
規定の一部ではありません。
この仕様書のそれ以外の部分はすべて規定の一部です。</span></p>

  <p class="has-ja-translation" data-ja-hash="8adc9958d29b879426b71b5b9eae46db"><span class=en-original lang=en>The key words "MUST", "MUST NOT", "REQUIRED", <!--"SHALL", "SHALL
  NOT",--> "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
  "OPTIONAL" in the normative parts of this document are to be
  interpreted as described in RFC2119. For readability, these words do
  not appear in all uppercase letters in this specification. <a href=#refsRFC2119>[RFC2119]</a></span><span class=ja-translation lang=ja>この文書の規定の部分にあるキーワード「<em class=rfc2119 title="MUST">しなければなりません</em>」、
「<em class=rfc2119 title="MUST NOT">してはなりません</em>」、
「<em class=rfc2119 title="REQUIRED">必須です</em>」、<!--"SHALL", "SHALL
  NOT",-->「<em class=rfc2119 title="SHOULD">するべきです</em>」、
「<em class=rfc2119 title="SHOULD NOT">するべきではありません</em>」、
「<em class=rfc2119 title="RECOMMENDED">推奨します</em>」、「<em class=rfc2119 title="MAY">して構いません</em>」、
「<em class=rfc2119 title="OPTIONAL">任意です</em>」は、 RFC 2119 で説明されているように解釈します。
この仕様書<ins class=ja-note>の原文</ins>では、
可読性の観点から、
これらの語<ins class=ja-note>の原語</ins>のすべて大文字による表記は行っていません。
<a href=#refsRFC2119>[RFC2119]</a></span></p>

  <p class="has-ja-translation" data-ja-hash="63dc4357c416e0e0f292a5f662ca71ab"><span class=en-original lang=en>Requirements phrased in the imperative as part of algorithms
  (such as "strip any leading space characters" or "return false and
  abort these steps") are to be interpreted with the meaning of the
  key word ("must", "should", "may", etc) used in introducing the
  algorithm.</span><span class=ja-translation lang=ja>算法の一部として<ins class=ja-note>動作の指示の形で (原文では</ins>命令形で<ins class=ja-note>) </ins>記述された要件
(例えば「先頭の間隔文字をすべて除去します」や「偽を返し、これらの段階を停止します」)
は、算法を紹介するに当たって使われたキーワード (<em class=rfc2119 title="MUST">しなければなりません</em>、
<em class=rfc2119 title="SHOULD">するべきです</em>、<em class=rfc2119 title="MAY">して構いません</em>など) の意味により解釈します。</span></p>

  <p class="has-ja-translation" data-ja-hash="a5a0db584980ce3f2448983d6188b2d1"><span class=en-original lang=en>Some conformance requirements are phrased as requirements on
  attributes, methods or objects. Such requirements are to be
  interpreted as requirements on user agents.</span><span class=ja-translation lang=ja>いくつかの適合性要件は属性やメソッドやオブジェクトの要件として説明されています。
そのような要件は、利用者エージェントに関する要件として解釈します。</span></p>

  <p class="has-ja-translation" data-ja-hash="27386c326b98d878b3c408c60b6095b0"><span class=en-original lang=en>Conformance requirements phrased as algorithms or specific steps
  may be implemented in any manner, so long as the end result is
  equivalent. (In particular, the algorithms defined in this
  specification are intended to be easy to follow, and not intended to
  be performant.)</span><span class=ja-translation lang=ja>算法や特定の段階として説明されている適合性要件は、
最終的な結果が等価である限り、任意の方法で実装して<em class=rfc2119 title="MAY">構いません</em>。
(特に、この仕様書で定義されている算法は追うのを簡単にしており、
高性能であることを目指してはいません。)</span></p>

  <p class="has-ja-translation" data-ja-hash="e42931a32a5e7ad458e3ca1b87d741d9"><span class=en-original lang=en>The only conformance class defined by this specification is user
  agents.</span><span class=ja-translation lang=ja>この仕様書で定義する唯一の適合性の級は利用者エージェントです。</span></p>

  <p class="has-ja-translation" data-ja-hash="57959e6c42e8d5141b11e501bf60cc2f"><span class=en-original lang=en>User agents may impose implementation-specific limits on
  otherwise unconstrained inputs, e.g. to prevent denial of service
  attacks, to guard against running out of memory, or to work around
  platform-specific limitations.</span><span class=ja-translation lang=ja>利用者エージェントは、サービス拒否攻撃を防ぐため、
記憶容量を使い尽くすことを防ぐため、
あるいは環境特有の制限に対応するためなどの目的で、
別段の制約のない入力に対して実装特有の制限を設けて<em class=rfc2119 title="MAY">構いません</em>。</span></p>


  <h3 id=dependencies class="has-ja-translation" data-ja-hash="896f4eaa4f12972b56ed9cdd9a90b949"><span class=en-original lang=en><span class=secno>2.1 </span>Dependencies</span><span class=ja-translation lang=ja><span class=secno>2.1 </span>依存性</span></h3>

  <p class="has-ja-translation" data-ja-hash="8dc27a34324d9e41d25c6bbbc2d2551c"><span class=en-original lang=en>This specification relies on several other underlying
  specifications.</span><span class=ja-translation lang=ja>この仕様書は、他のいくつかの下位の仕様書に依存しています。</span></p>

  <dl><dt class="no-ja-translation" data-ja-hash="6bff62b10d884fb77428cfe168cd783d"><span class=en-original lang=en>HTML5</span></dt>

   <dd>

    <p class="has-ja-translation" data-ja-hash="99d7a97f59faf316f6125ad288390f21"><span class=en-original lang=en>Many fundamental concepts from HTML5 are used by this
    specification. <a href=#refsHTML5>[HTML5]</a></span><span class=ja-translation lang=ja>この仕様書では、 HTML5 の多くの基礎的な概念を使用します。
<a href=#refsHTML5>[HTML5]</a></span></p>

   </dd>

   <dt class="no-ja-translation" data-ja-hash="21838f6e93b1a2157b16dcb6281ff225"><span class=en-original lang=en>WebIDL</span></dt>

   <dd>

    <p class="no-ja-translation" data-ja-hash="336ded24806a8bd7c04c235bef4cd598"><span class=en-original lang=en>The IDL blocks in this specification use the semantics of the
    WebIDL specification. <a href=#refsWEBIDL>[WEBIDL]</a></span></p>

   </dd>

  </dl><h2 id=terminology class="has-ja-translation" data-ja-hash="e182a8a3f2adf774fb1c959df71b8600"><span class=en-original lang=en><span class=secno>3 </span>Terminology</span><span class=ja-translation lang=ja><span class=secno>3 </span>用語</span></h2>

  <p class="has-ja-translation" data-ja-hash="f99630e4a7f12f2c4ecb88e02bf4a644"><span class=en-original lang=en>The construction "a <code title="">Foo</code> object", where
  <code title="">Foo</code> is actually an interface, is sometimes
  used instead of the more accurate "an object implementing the
  interface <code title="">Foo</code>".</span><span class=ja-translation lang=ja>「<code title="">Foo</code> オブジェクト」という構文 (<code title="">Foo</code>
は実際には界面) を時々使いますが、より正確な「界面 <code title="">Foo</code>
を実装しているオブジェクト」の代わりに用いています。</span></p>

  <p class="no-ja-translation" data-ja-hash="53202e038bee25bf5bb2edbf37c7cdce"><span class=en-original lang=en>The term DOM is used to refer to the API set made available to
  scripts in Web applications, and does not necessarily imply the
  existence of an actual <code>Document</code> object or of any other
  <code>Node</code> objects as defined in the DOM Core
  specifications. <a href=#refsDOMCORE>[DOMCORE]</a></span></p>

  <p class="has-ja-translation" data-ja-hash="5b9242da79aeab74bccc57781ac3103e"><span class=en-original lang=en>A DOM attribute is said to be <em>getting</em> when its value is
  being retrieved (e.g. by author script), and is said to be
  <em>setting</em> when a new value is assigned to it.</span><span class=ja-translation lang=ja>DOM 属性は、その値が (例えば著者のスクリプトにより) 取り出される時<em>取得される</em>といい、
新しい値がその属性に割り当てられる時<em>設定される</em>といいます。</span></p>

  <p class="no-ja-translation" data-ja-hash="63fe78b97a0b5051e1ffbf6ee2f1e483"><span class=en-original lang=en>The term "JavaScript" is used to refer to ECMA262, rather than
  the official term ECMAScript, since the term JavaScript is more
  widely known. <a href=#refsECMA262>[ECMA262]</a></span></p>


  <h2 id=infrastructure class="has-ja-translation" data-ja-hash="cba4f4cee5c6a3e6d8be8da68fa1234e"><span class=en-original lang=en><span class=secno>4 </span>Infrastructure</span><span class=ja-translation lang=ja><span class=secno>4 </span>基盤</span></h2>

  <p class="no-ja-translation" data-ja-hash="f38a96d03c61f343169a402b5c779db8"><span class=en-original lang=en>There are two kinds of workers; dedicated workers, and shared
  workers. Dedicated workers, once created, and are linked to their
  creator; but message ports can be used to communicate from a
  dedicated worker to multiple other browsing contexts or
  workers. Shared workers, on the other hand, are named, and once
  created any script running in the same <span>origin</span> can
  obtain a reference to that worker and communicate with it.</span></p>


  <h3 id=the-global-scope class="has-ja-translation" data-ja-hash="16d7670f16b3aaf6130252e8f11702eb"><span class=en-original lang=en><span class=secno>4.1 </span>The global scope</span><span class=ja-translation lang=ja><span class=secno>4.1 </span>大域作用域</span></h3>

  <p class="has-ja-translation" data-ja-hash="216dee088449fef485a489ea8a7432f4"><span class=en-original lang=en>The global scope is the "inside" of a worker.</span><span class=ja-translation lang=ja>大域作用域は労働者の「内側」です。</span></p>

  <h4 id=the-workerglobalscope-abstract-interface class="has-ja-translation" data-ja-hash="fe5227371e801f4ac588d0d07472a900" data-ja-real-hash="be491e4df478a7115eae60853f3c23aa"><span class=en-original lang=en><span class=secno>4.1.1 </span>The <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> abstract interface</span><span class=ja-translation lang=ja><span class=secno>4.1.1 </span><code><a href=#workerglobalscope>WorkerGlobalScope</a></code> 抽象界面</span></h4>

  <pre class="idl no-ja-translation" data-ja-hash="e3d0f4444473b31bbffb7bd44e6f1016"><span class=en-original lang=en>interface <dfn id=workerglobalscope>WorkerGlobalScope</dfn> {
  readonly attribute <a href=#workerglobalscope>WorkerGlobalScope</a> <a href=#dom-workerglobalscope-self title=dom-WorkerGlobalScope-self>self</a>;
  readonly attribute <a href=#workerlocation>WorkerLocation</a> <a href=#dom-workerglobalscope-location title=dom-WorkerGlobalScope-location>location</a>;

  void <a href=#dom-workerglobalscope-close title=dom-WorkerGlobalScope-close>close</a>();
<!-- v2-onclose           attribute <span>Function</span> <span title="handler-WorkerGlobalScope-onclose">onclose</span>;
-->           attribute <span>Function</span> <a href=#handler-workerglobalscope-onerror title=handler-WorkerGlobalScope-onerror>onerror</a>;
};
<a href=#workerglobalscope>WorkerGlobalScope</a> implements <a href=#workerutils>WorkerUtils</a>;</span></pre>

  <p class="no-ja-translation" data-ja-hash="d82fd6989aa746efef0cf182479d5e41"><span class=en-original lang=en>Objects implementing the <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> interface
  must also implement the <code>EventTarget</code> interface.</span></p>

  <p class="no-ja-translation" data-ja-hash="0a5104552951765122b762e943a821b0"><span class=en-original lang=en>The <dfn id=dom-workerglobalscope-self title=dom-WorkerGlobalScope-self><code>self</code></dfn> attribute
  must return the <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object itself.</span></p>

  <p class="no-ja-translation" data-ja-hash="e48d78d83311d57328ab69a17167fffc"><span class=en-original lang=en>The <dfn id=dom-workerglobalscope-location title=dom-WorkerGlobalScope-location><code>location</code></dfn>
  attribute must return the <code><a href=#workerlocation>WorkerLocation</a></code> object created
  for the <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object when the worker was
  created. It represents the <span>absolute URL</span> of the script
  that was used to initialize the worker, after any redirects.</span></p>

  <hr><p class="no-ja-translation" data-ja-hash="c205c04fbfcc56617b82329c66dbda4a"><span class=en-original lang=en>When a script invokes the <dfn id=dom-workerglobalscope-close title=dom-WorkerGlobalScope-close><code>close()</code></dfn>
  method on a <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object, the user agent
  must run the following steps (atomically):</span></p>

  <ol><li><p class="no-ja-translation" data-ja-hash="af4d5ddb9edfb1a69b29ed3140620794"><span class=en-original lang=en>Discard any <span title=concept-task>tasks</span> that
   have been added to the <span>event loop</span>'s <span title="task
   queue">task queues</span>.</span></p>

<!-- v2-onclose
   <li><p class="no-ja-translation" data-ja-hash="8d73b86033e135135fa4dd2f2193b43e"><span class=en-original lang=en><span>Queue a task</span> to <span>fire a simple
   event</span> called <code title="event-close">close</code> at the
   <code>WorkerGlobalScope</code> object.</span></p></li>
-->

   <li><p class="no-ja-translation" data-ja-hash="1e713e7163b783674600c93aed418557"><span class=en-original lang=en>Set the worker's <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object's
   <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag to
   true. (This prevents any further tasks from being queued.)</span></li>

   <li><p class="no-ja-translation" data-ja-hash="37da2c132b44ba85602699d1ef93c598"><span class=en-original lang=en>Disentangle all the ports in the list of <a href="#the-worker's-ports">the worker's
   ports</a>.</span></li>

  </ol><p class="no-ja-translation" data-ja-hash="a8c40bcd77a6115776143cfb3b3d6432"><span class=en-original lang=en>The following are the <span>event handler attributes</span> (and their corresponding <span title="event handler event type">event handler event types</span>)
  that must be supported, as IDL attributes, by objects implementing
  the <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> interface:</span></p>

  <table><thead><tr><th class="no-ja-translation" data-ja-hash="c85726f0c6ba202006ec1f912e68aa76"><span class=en-original lang=en><span title="event handler attributes">event handler attribute</span> </span><th class="no-ja-translation" data-ja-hash="3fc98eebba71602c62d8b2fd74645dc9"><span class=en-original lang=en><span>Event handler event type</span>
   </span><tbody><!-- v2-onclose    <tr><td class="no-ja-translation" data-ja-hash="8299f4100f9c690ddf7935714f58b453"><span class=en-original lang=en><dfn title="handler-WorkerGlobalScope-onclose"><code>onclose</code></dfn> </span><td class="no-ja-translation" data-ja-hash="e899358e829911a25c083ed9bc6519e6"><span class=en-original lang=en> <code title="event-close">close</code> --></span><tr><td class="no-ja-translation" data-ja-hash="08a21be8031dd240d32ac8ab2b17a9ac"><span class=en-original lang=en><dfn id=handler-workerglobalscope-onerror title=handler-WorkerGlobalScope-onerror><code>onerror</code></dfn> </span><td class="no-ja-translation" data-ja-hash="bf1b78c16e7c3a3de662d83f487bffff"><span class=en-original lang=en> <code title=event-error>error</code>
  </span></table><h4 id=dedicated-workers-and-the-dedicatedworkerglobalscope-interface class="no-ja-translation" data-ja-hash="a4b427f41de050a77385a1705efbb7c1"><span class=en-original lang=en><span class=secno>4.1.2 </span>Dedicated workers and the <code><a href=#dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</a></code> interface</span></h4>

  <pre class="idl no-ja-translation" data-ja-hash="bfd4cc74d5de30a3a56b69105fa0d527"><span class=en-original lang=en>[Supplemental, NoInterfaceObject]
interface <dfn id=dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</dfn> : <a href=#workerglobalscope>WorkerGlobalScope</a> {
  void <a href=#dom-dedicatedworkerglobalscope-postmessage title=dom-DedicatedWorkerGlobalScope-postMessage>postMessage</a>(in any message, optional in <span>MessagePortArray</span> ports);<!--
  <span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
           attribute <span>Function</span> <a href=#handler-dedicatedworkerglobalscope-onmessage title=handler-DedicatedWorkerGlobalScope-onmessage>onmessage</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="2b76e99642dd9984f9a5fb8a280c921c"><span class=en-original lang=en><code><a href=#dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</a></code> objects act as if they
  had an implicit <code>MessagePort</code> associated with them. This
  port is part of a channel that is set up when the worker is created,
  but it is not exposed. This object must never be garbage collected
  before the <code><a href=#dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</a></code> object.</span></p>

  <p class="no-ja-translation" data-ja-hash="3737098ad5998864275d8ee619bd864e"><span class=en-original lang=en>All messages received by that port must immediately be retargeted
  at the <code><a href=#dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</a></code> object.</span></p>

  <p class="no-ja-translation" data-ja-hash="8156ab5347965f42a9531625b8096a00"><span class=en-original lang=en>The <dfn id=dom-dedicatedworkerglobalscope-postmessage title=dom-DedicatedWorkerGlobalScope-postMessage><code>postMessage()</code></dfn><!--
  and <dfn
  title="dom-DedicatedWorkerGlobalScope-startConversation"><code>startConversation()</code></dfn>-->
  method<!--s (startConversation)--> on
  <code><a href=#dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</a></code> objects must act as if, when
  invoked, it<!--/they (startConversation)--> immediately invoked the
  method of the same name on the port, with the same arguments, and
  returned the same return value.</span></p>

  <p class="no-ja-translation" data-ja-hash="9f916c945eaba748068930865e3fe032"><span class=en-original lang=en>The following are the <span>event handler attributes</span> (and
  their corresponding <span title="event handler event type">event
  handler event types</span>) that must be supported, as IDL
  attributes, by objects implementing the
  <code><a href=#dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</a></code> interface:</span></p>

  <table><thead><tr><th class="no-ja-translation" data-ja-hash="c85726f0c6ba202006ec1f912e68aa76"><span class=en-original lang=en><span title="event handler attributes">event handler attribute</span> </span><th class="no-ja-translation" data-ja-hash="3fc98eebba71602c62d8b2fd74645dc9"><span class=en-original lang=en><span>Event handler event type</span>
   </span><tbody><tr><td class="no-ja-translation" data-ja-hash="0d8bd2da6a52d641c317fac6d1c953b2"><span class=en-original lang=en><dfn id=handler-dedicatedworkerglobalscope-onmessage title=handler-DedicatedWorkerGlobalScope-onmessage><code>onmessage</code></dfn> </span><td class="no-ja-translation" data-ja-hash="fe07e2527bf13c457386ab4807af84a0"><span class=en-original lang=en> <code title=event-message>message</code>
  </span></table><p class="no-ja-translation" data-ja-hash="0c348925ec14031682913edd79ceb3d3"><span class=en-original lang=en>For the purposes of the <span>offline application cache</span>
  networking model, a dedicated worker is an extension of the
  <span>cache host</span> from which it was created.</span></p>


  <h4 id=shared-workers-and-the-sharedworkerglobalscope-inteface class="no-ja-translation" data-ja-hash="6ab8095d66816337c244beec43a0e6d4"><span class=en-original lang=en><span class=secno>4.1.3 </span>Shared workers and the <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code> inteface</span></h4>

  <pre class="idl no-ja-translation" data-ja-hash="d50871df68a2c60553b6a55d6cd199bc"><span class=en-original lang=en>[Supplemental, NoInterfaceObject]
interface <dfn id=sharedworkerglobalscope>SharedWorkerGlobalScope</dfn> : <a href=#workerglobalscope>WorkerGlobalScope</a> {
  readonly attribute DOMString <a href=#dom-sharedworkerglobalscope-name title=dom-SharedWorkerGlobalScope-name>name</a>;
  readonly attribute <span>ApplicationCache</span> <a href=#dom-sharedworkerglobalscope-applicationcache title=dom-SharedWorkerGlobalScope-applicationCache>applicationCache</a>;
           attribute <span>Function</span> <a href=#handler-sharedworkerglobalscope-onconnect title=handler-SharedWorkerGlobalScope-onconnect>onconnect</a>;
};</span></pre>

  <p class="has-ja-translation" data-ja-hash="9d344498c69a5ed60029b76fb274beb2"><span class=en-original lang=en>Shared workers receive message ports through <code title=event-WorkerGlobalScope-connect>connect</code> events on
  their global object for each connection.</span><span class=ja-translation lang=ja>共有労働者は、各接続について大域オブジェクトの <code
   title=event-WorkerGlobalScope-connect>connect</code> 事象を通じてメッセージ・ポートを受信します。</span></p>

  <p class="no-ja-translation" data-ja-hash="582a890c60947f33bddb73ed33bb32f9"><span class=en-original lang=en>The <dfn id=dom-sharedworkerglobalscope-name title=dom-SharedWorkerGlobalScope-name><code>name</code></dfn>
  attribute must return the value it was assigned when the
  <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code> object was created by the
  "<a href=#run-a-worker>run a worker</a>" algorithm. Its value represents the name
  that can be used to obtain a reference to the worker using the
  <code><a href=#sharedworker>SharedWorker</a></code> constructor.</span></p>

  <p class="no-ja-translation" data-ja-hash="340c4ff434e093d2b3cb012e0ece11a7"><span class=en-original lang=en>The following are the <span>event handler attributes</span> (and
  their corresponding <span title="event handler event type">event
  handler event types</span>) that must be supported, as IDL
  attributes, by objects implementing the
  <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code> interface:</span></p>

  <table><thead><tr><th class="no-ja-translation" data-ja-hash="c85726f0c6ba202006ec1f912e68aa76"><span class=en-original lang=en><span title="event handler attributes">event handler attribute</span> </span><th class="no-ja-translation" data-ja-hash="3fc98eebba71602c62d8b2fd74645dc9"><span class=en-original lang=en><span>Event handler event type</span>
   </span><tbody><tr><td class="no-ja-translation" data-ja-hash="f198960aead81a70dcfd8fe22ce3e5c3"><span class=en-original lang=en><dfn id=handler-sharedworkerglobalscope-onconnect title=handler-SharedWorkerGlobalScope-onconnect><code>onconnect</code></dfn> </span><td class="no-ja-translation" data-ja-hash="01a017777bf3db29f5ec26ca1ad7aced"><span class=en-original lang=en> <code title=event-connect>connect</code>
  </span></table><p class="no-ja-translation" data-ja-hash="ac81324d4bd9e8a1090d3db7e2e34ca9"><span class=en-original lang=en>For the purposes of the <span>offline application cache</span>
  networking model, a shared worker is its own <span>cache
  host</span>. The <a href=#run-a-worker>run a worker</a> algorithm takes care of
  associating the worker with an <span>application cache</span>.</span></p>

  <p class="note no-ja-translation" data-ja-hash="eb3d6f833d8fb42a6cea6890baeaf796"><span class=en-original lang=en>The <dfn id=dom-sharedworkerglobalscope-applicationcache title=dom-SharedWorkerGlobalScope-applicationCache><code>applicationCache</code></dfn>
  attribute returns the <code>ApplicationCache</code> object for the
  worker.</span></p><!-- normative conf criteria is in the appcache section
  -->


  <h3 id=origins-of-workers class="no-ja-translation" data-ja-hash="f13b3937c992e49f9b4feea9b2724a18"><span class=en-original lang=en><span class=secno>4.2 </span>Origins of workers</span></h3>

  <p class="no-ja-translation" data-ja-hash="5d71247ae9c7e88e4244d78062ed4760"><span class=en-original lang=en>Both the <span>origin</span> and <span>effective script
  origin</span> of scripts running in workers are the
  <span>origin</span> of the <span>absolute URL</span> given in that
  the worker's <code title=dom-WorkerGlobalScope-location><a href=#dom-workerglobalscope-location>location</a></code> attribute
  represents.</span></p>


  <h3 id=decoding-scripts class="no-ja-translation" data-ja-hash="857fdf8086147b470ea754e3a4f6c667"><span class=en-original lang=en><span class=secno>4.3 </span>Decoding scripts</span></h3>

  <p class="no-ja-translation" data-ja-hash="4356cf7102f2b838e2b8201769e8d8ed"><span class=en-original lang=en>When a user agent is to <dfn id=decode-a-script-resource>decode a script resource</dfn> to
  obtain its source in Unicode, it must run the following steps:</span></p>

  <ol><li>

    <p class="no-ja-translation" data-ja-hash="6571036d6f54aff003088a24c671dfc7"><span class=en-original lang=en>Let <var title="">character encoding</var> be <i title="">unknown</i>.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="26531f4017a22df14ccb6d1eee6264e7"><span class=en-original lang=en>For each of the rows in the following table, starting with the
    first one and going down, if the resource has as many or more
    bytes available than the number of bytes in the first column, and
    the first bytes of the resource match the bytes given in the first
    column, then let <var title="">character encoding</var> be the
    encoding given in the cell in the second column of that row:</span></p>

    <!-- this table is present in several forms in this file; keep them in sync -->
    <table><thead><tr><th class="has-ja-translation" data-ja-hash="cedd90a7eefcd8a4c28ead96824a8c5a"><span class=en-original lang=en>Bytes in Hexadecimal
       </span><span class=ja-translation lang=ja>バイトの十六進数表現</span><th class="has-ja-translation" data-ja-hash="169a6f6b44766410bffebf76ff3dcf17"><span class=en-original lang=en>Encoding
     </span><span class=ja-translation lang=ja>符号化</span><tbody><!-- nobody uses this
      <tr>
       <td class="no-ja-translation" data-ja-hash="3b523bf4f5c7a5f0ff3963fdad8049a9"><span class=en-original lang=en>00 00 FE FF
       </span><td class="no-ja-translation" data-ja-hash="59e7c7bf45f69d917450ae560a578a4f"><span class=en-original lang=en>UTF-32BE
      </span><tr>
       <td class="no-ja-translation" data-ja-hash="e25d985f134390f54047573f4a1eca7e"><span class=en-original lang=en>FF FE 00 00
       </span><td class="no-ja-translation" data-ja-hash="83039ece36f32fba267280c8de26edf5"><span class=en-original lang=en>UTF-32LE
--></span><tr><td class="no-ja-translation" data-ja-hash="d9594f5bb7f7387cd1c6d8cb69fb5774"><span class=en-original lang=en>FE FF
       </span><td class="no-ja-translation" data-ja-hash="58ee3e3038c435c19dfa106ac8b67d73"><span class=en-original lang=en>UTF-16BE
      </span><tr><td class="no-ja-translation" data-ja-hash="3d748bc0fd7caa28cb9bd697c840f46f"><span class=en-original lang=en>FF FE
       </span><td class="no-ja-translation" data-ja-hash="600ebb464ff7e548ff5a09c2c12f551b"><span class=en-original lang=en>UTF-16LE
      </span><tr><td class="no-ja-translation" data-ja-hash="5d1b4e645efa35016b709ffbd308e29d"><span class=en-original lang=en>EF BB BF
       </span><td class="no-ja-translation" data-ja-hash="ae3b3df9970b49b6523e608759bc957d"><span class=en-original lang=en>UTF-8
<!-- nobody uses this
      --></span><!--<tr>
       <td class="no-ja-translation" data-ja-hash="7d1cd1d79b5ca7151c2153c016bc5c49"><span class=en-original lang=en>DD 73 66 73
       </span><td class="no-ja-translation" data-ja-hash="48ad579645de9a10a9a6f78fab81fb65"><span class=en-original lang=en>UTF-EBCDIC
-->
    </span></table><p class="note no-ja-translation" data-ja-hash="9a59482dc82872c443907eeed8818b89"><span class=en-original lang=en>This step looks for Unicode Byte Order Marks
    (BOMs).</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="1bdaa4e7198023dcf4f7984a4898619a"><span class=en-original lang=en>If <var title="">character encoding</var> is still <i title="">unknown</i>, apply the <span>algorithm for extracting an
    encoding from a Content-Type</span> to the resource's <span title=Content-Type>Content Type metadata</span>; if this returns
    an encoding, and the user agent supports that encoding, then let
    <var title="">character encoding</var> be that encoding.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="6bbc467e6929571d61a6b95004cf9974"><span class=en-original lang=en>If <var title="">character encoding</var> is still <i title="">unknown</i>, then let <var title="">character
    encoding</var> be UTF-8.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="178b2c0b2c79b7e38b80e13f0fac6983"><span class=en-original lang=en>Convert the resource to Unicode using the character encoding
    given by <var title="">character encoding</var>.</span></p>

    <p class="no-ja-translation" data-ja-hash="ee427dae6dec0a6bf731b3069f9a4abd"><span class=en-original lang=en>Return the text that is so obtained.</span></p>

   </li>

  </ol><h3 id=the-event-loop class="no-ja-translation" data-ja-hash="96715962ce61ea28085d7e170ec30e73"><span class=en-original lang=en><span class=secno>4.4 </span>The event loop</span></h3>

  <p class="no-ja-translation" data-ja-hash="9da3324200d63a62412fc5bc671f7d95"><span class=en-original lang=en>Each <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object has an <span>event
  loop</span> distinct from those defined for <span title="unit of
  related similar-origin browsing contexts">units of related
  similar-origin browsing contexts</span>. This <span>event
  loop</span> has no associated <span>browsing context</span>, and its
  <span title="task queue">task queues</span> only have events,
  callbacks, and networking activity as <span title=concept-task>tasks</span>. The processing model of these
  <span title="event loop">event loops</span> is defined below in the
  <a href=#run-a-worker>run a worker</a> algorithm.</span></p>

  <p class="no-ja-translation" data-ja-hash="084ed34f256b8b7e4ff2b85cd92ca33b"><span class=en-original lang=en>Each <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object also has a <dfn id=dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</dfn> flag, which must
  initially be false, but which can get set to true by the algorithms
  in the processing model section below.</span></p>

  <p class="no-ja-translation" data-ja-hash="35f0c99f177dce8acd9669a371da6ba3"><span class=en-original lang=en>Once the <code><a href=#workerglobalscope>WorkerGlobalScope</a></code>'s <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag is set to
  true, the <span>event loop</span>'s <span title="task queue">task
  queues</span> must discard any further <span title=concept-task>tasks</span> that would be added to them (tasks
  already on the queue are unaffected unless otherwise
  specified). Effectively, once the <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag is true,
  timers stop firing, notifications for all pending asynchronous
  operations are dropped, etc.</span></p>


  <h3 id="the-worker's-lifetime" class="no-ja-translation" data-ja-hash="74a0efe3050847567026cd8638e4d2d6"><span class=en-original lang=en><span class=secno>4.5 </span>The worker's lifetime</span></h3>

  <p class="has-ja-translation" data-ja-hash="15eb0638e0de7d0e159c1214c48ba569"><span class=en-original lang=en>Workers communicate with other workers and with <span title="browsing context">browsing contexts</span> through <span title="channel messaging">message channels</span> and their
  <code>MessagePort</code> objects.</span><span class=ja-translation lang=ja>労働者は、メッセージ通信路とその <code>MessagePort</code>
オブジェクトを通じて、他の労働者や閲覧文脈と通信します。</span></p>

  <p class="no-ja-translation" data-ja-hash="2c7d1a4ce717326e596bad596f0fc0bb"><span class=en-original lang=en>Each <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> <var title="">worker global
  scope</var> has a list of <dfn id="the-worker's-ports">the worker's ports</dfn>, which
  consists of all the <code>MessagePort</code> objects that are
  entangled with another port and that have one (but only one) port
  owned by <var title="">worker global scope</var>. This list includes
  <!--all the <code>MessagePort</code> objects that are in events
  pending in the <span>event loop</span>, as well as (commented out
  because in practice it makes no difference either way as far as I
  can tell, and it would be hard to strictly implement since these
  ports might not yet be across the thread boundary)--> the implicit
  <code>MessagePort</code> in the case of <a href=#dedicatedworkerglobalscope title=DedicatedWorkerGlobalScope>dedicated workers</a>.</span></p>

  <p class="no-ja-translation" data-ja-hash="1aeb90a4b706e7a9ff09953cd49aed7c"><span class=en-original lang=en>Each <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> also has a list of <dfn id="the-worker's-workers">the
  worker's workers</dfn>. Initially this list is empty; it is
  populated when the worker creates or obtains further workers.</span></p>

  <p class="no-ja-translation" data-ja-hash="065bd87a93010cf4e435c95f2e540af5"><span class=en-original lang=en>Finally, each <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> also has a list of
  <dfn id="the-worker's-documents">the worker's <code>Document</code>s</dfn>. Initially this list
  is empty; it is populated when the worker is created.</span></p>

  <p class="no-ja-translation" data-ja-hash="6a8fe8066ddde02f0b3e6e22079bbd7e"><span class=en-original lang=en>Whenever a <code>Document</code> <var title="">d</var> is <dfn id="add-a-document-to-the-worker's-documents" title="add a document to the worker's documents">added to the
  worker's <code>Document</code>s</dfn>, the user agent must, for each
  worker in the list of <a href="#the-worker's-workers">the worker's workers</a> whose list
  of <a href="#the-worker's-documents">the worker's <code>Document</code>s</a> does not contain
  <var title="">d</var>, <a href="#add-a-document-to-the-worker's-documents" title="add a document to the worker's
  documents">add <var title="">d</var> to <var title="">q</var>'s
  <code>WorkerGlobalScope</code> owner's list of <span>the worker's
  <code>Document</code>s</span></a>.</span></p> <!-- suggestions welcome
  on making this sentence into understandable English -->

  <p class="no-ja-translation" data-ja-hash="c556389e6b192b4ac768940df1b3cffc"><span class=en-original lang=en>Whenever a <code>Document</code> object is <span title="discard a
  Document">discarded</span>, it must be removed from the list of
  <a href="#the-worker's-documents">the worker's <code>Document</code>s</a> of each worker
  whose list contains that <code>Document</code>.</span></p>

  <p class="no-ja-translation" data-ja-hash="db482587a227e92fd91bc6be1c81ddb3"><span class=en-original lang=en>Given a <span>script's global scope</span> <var title="">o</var>
  when creating or obtaining a worker, the <dfn id=list-of-relevant-document-objects-to-add>list of relevant
  <code>Document</code> objects to add</dfn> depends on the type of
  <var title="">o</var>. If <var title="">o</var> is a
  <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object (i.e. if we are creating a
  nested worker), then the relevant <code>Document</code>s are the
  <code>Document</code>s that are in <var title="">o</var>'s own list
  of <a href="#the-worker's-documents">the worker's <code>Document</code>s</a>. Otherwise, <var title="">o</var> is a <code>Window</code> object, and the relevant
  <code>Document</code> is just the <code>Document</code> that is the
  <span>active document</span> of the <code>Window</code> object <var title="">o</var>.</span></p>

  <hr><p class="no-ja-translation" data-ja-hash="ea771ae7f86ae7c85f1418763117fa28"><span class=en-original lang=en>A worker is said to be a <dfn id=permissible-worker>permissible worker</dfn> if its
  list of <a href="#the-worker's-documents">the worker's <code>Document</code>s</a> is not
  empty.</span></p>

  <p class="no-ja-translation" data-ja-hash="e7407e6349a298d2bf4d87d06d147420"><span class=en-original lang=en>A worker is said to be a <dfn id=protected-worker>protected worker</dfn> if it is a
  <a href=#permissible-worker>permissible worker</a> and either it has outstanding
  timers, database transactions, or network connections, or its list
  of <a href="#the-worker's-ports">the worker's ports</a> is not empty, or its
  <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> is actually a
  <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
  shared worker).</span></p>

  <p class="no-ja-translation" data-ja-hash="1a7b06a4fed1c22378b6b6f6ca13ffc2"><span class=en-original lang=en>A worker is said to be an <dfn id=active-needed-worker>active needed worker</dfn> if any
  of the <code>Document</code> objects in <a href="#the-worker's-documents">the worker's
  <code>Document</code>s</a> are <span>fully active</span>.</span></p>

  <p class="no-ja-translation" data-ja-hash="4182e47a8cba3978170630845be09eed"><span class=en-original lang=en>A worker is said to be a <dfn id=suspendable-worker>suspendable worker</dfn> if it is
  not an <a href=#active-needed-worker>active needed worker</a> but it is a
  <a href=#permissible-worker>permissible worker</a>.</span></p>


  <h3 id=processing-model class="has-ja-translation" data-ja-hash="4eeffb677544f6c8799408c6b9021b4c"><span class=en-original lang=en><span class=secno>4.6 </span>Processing model</span><span class=ja-translation lang=ja><span class=secno>4.6 </span>処理モデル</span></h3>

  <p class="no-ja-translation" data-ja-hash="c45c1611a5572d560022f94383f4daf7"><span class=en-original lang=en>When a user agent is to <dfn id=run-a-worker>run a worker</dfn> for a script with
  <span>URL</span> <var title="">url</var>, a browsing context <var title="">owner browsing context</var>, and with global scope <var title="">worker global scope</var>, it must run the following
  steps:</span></p>

  <ol><li>

    <p class="no-ja-translation" data-ja-hash="699e58187adc9ee37990500a66c83a8f"><span class=en-original lang=en>Create a completely separate and parallel execution environment
    (i.e. a separate thread or process or equivalent construct), and
    run the rest of these steps asynchronously in that context.</span></p>

   </li>

   <li><p class="no-ja-translation" data-ja-hash="d41742425aaafe5999e11ca90b26f088"><span class=en-original lang=en>If <var title="">worker global scope</var> is actually a
   <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code> object (i.e. the worker is a
   shared worker), and there are any <span title="relevant application
   cache">relevant application caches</span> that are identified by a
   manifest URL with the <span>same origin</span> as <var title="">url</var> and that have <var title="">url</var> as one of
   their entries, <em>not</em> excluding entries marked as <span title=concept-appcache-foreign>foreign</span>, then associate the
   <var title="">worker global scope</var> with the <span title=concept-appcache-selection>most appropriate application
   cache</span> of those that match.</span></li>

   <li>

    <p class="no-ja-translation" data-ja-hash="83920af54821d7c307267e9565d86ea3"><span class=en-original lang=en>Attempt to <span>fetch</span> the resource identified by <var title="">url</var>.</span></p>

    <p class="no-ja-translation" data-ja-hash="26478052fa0ac3c2e89f64956f73b55f"><span class=en-original lang=en>If the attempt fails, or if the attempt involves any redirects
    to URIs that do not have the <span>same origin</span> as <var title="">url</var> (even if the final URI is at the <span>same
    origin</span> as the original <var title="">url</var>), then for
    each <code><a href=#worker>Worker</a></code> or <code><a href=#sharedworker>SharedWorker</a></code> object
    associated with <var title="">worker global scope</var>,
    <span>queue a task</span> to <span>fire a simple event</span>
    called <code title=event-error>error</code> at that
    object. Abort these steps.</span></p>

    <p class="no-ja-translation" data-ja-hash="a2c139226de4390d75b561512be824a7"><span class=en-original lang=en>If the attempt succeeds, then <a href=#decode-a-script-resource title="decode a script
    resource">decode the script resource</a> to obtain its <var title="">source</var>.</span></p>

    <p class="no-ja-translation" data-ja-hash="c880bce97c5a1aadccd8989fc4ec8551"><span class=en-original lang=en>Let <var title="">language</var> be JavaScript.</span></p>

    <p class="note has-ja-translation" data-ja-hash="5ba762159d9de3f8bd326fe0bcfac206"><span class=en-original lang=en>As with <code>script</code> elements, the MIME
    type of the script is ignored. Unlike with <code>script</code>
    elements, there is no way to override the type. It's always
    assumed to be JavaScript.</span><span class=ja-translation lang=ja><code>script</code> 要素と同様に、スクリプトの MIME 型は無視します。
<code>script</code> 要素とは異なり、
型を上書きする方法はありません。スクリプトは常に JavaScript
と仮定します。</span></p> <!-- XXX people will complain about
    this. I guess we might want to examine the MIME type... -->

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="604d3f52a6756f627f0e747b0d06e6ae"><span class=en-original lang=en>A new <span title=concept-script>script</span> is now
    created, as follows.</span></p>

    <p class="no-ja-translation" data-ja-hash="2dfcd0f76cde607de6cc88d70f390825"><span class=en-original lang=en>Create a new <span>script execution environment</span>
    set up as appropriate for the scripting language <var title="">language</var>.</span></p>

    <p class="no-ja-translation" data-ja-hash="fdf8b5f9ba18a31a8f48670142f51442"><span class=en-original lang=en>Parse/compile/initialize <var title="">source</var> using that
    <span>script execution environment</span>, as appropriate for <var title="">language</var>, and thus obtain a <span>list of code
    entry-points</span>; set the <i>initial code entry-point</i> to
    the entry-point for any executable code to be immediately run.</span></p>

    <p class="no-ja-translation" data-ja-hash="129927904de4572e52f5bc380711aa10"><span class=en-original lang=en>Set the <span>script's global object</span> to <var title="">worker global scope</var>.</span></p>

    <p class="no-ja-translation" data-ja-hash="02eeb9a0f925368a93666886c94bf9bf"><span class=en-original lang=en>Set the <span>script's browsing context</span> to <var title="">owner browsing context</var>.</span></p>

    <p class="no-ja-translation" data-ja-hash="104fe9ff67aec2141cd0733499cfef92"><span class=en-original lang=en>Set the <span>script's URL character encoding</span> to
    UTF-8. (This is just used for encoding non-ASCII characters in the
    query component of URLs.)</span></p>

    <p class="no-ja-translation" data-ja-hash="7570c80d1bbf45f73eb74befed51740d"><span class=en-original lang=en>Set the <span>script's base URL</span> to <var title="">url</var>.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="6ae721aad21a83f4d53f37c8e20baaf4"><span class=en-original lang=en><strong>Closing orphan workers</strong>: Start monitoring the
    worker such that no sooner than it stops being either a
    <a href=#protected-worker>protected worker</a> or a <a href=#suspendable-worker>suspendable
    worker</a>, and no later than it stops being a
    <a href=#permissible-worker>permissible worker</a>, <var title="">worker global
    scope</var>'s <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag is set
    to true<!-- v2-onclose and <span title="queue a task">a task is
    queued</span> to <span>fire a simple event</span> called <code
    title="event-close">close</code> at <var title="">worker global
    scope</var>-->.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="24a8fa04f32239e0dafc1e98e466d6b4"><span class=en-original lang=en><strong>Suspending workers</strong>: Start monitoring the
    worker, such that whenever <var title="">worker global
    scope</var>'s <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag is false
    and the worker is a <a href=#suspendable-worker>suspendable worker</a>, the user
    agent suspends execution of script in that worker until such time
    as either the <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag switches
    to true or the worker stops being a <a href=#suspendable-worker>suspendable
    worker</a>.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="4321156bbce7d4613215c6cd962a1dc4"><span class=en-original lang=en><span title="jump to a code entry-point">Jump</span> to the
    <span title=concept-script>script</span>'s <i>initial code
    entry-point</i>, and let that run until it either returns, fails
    to catch an exception, or gets prematurely aborted by the
    "<a href=#kill-a-worker>kill a worker</a>" or "<a href=#terminate-a-worker>terminate a worker</a>"
    algorithms defined below.</span></p>

<!-- v2-onclose
    <p class="note no-ja-translation" data-ja-hash="e632e340409f851c9423aafe27afe24f"><span class=en-original lang=en>If the script gets aborted by the "<span>kill a
    worker</span>" algorithm, then that same algorithm will cause
    there to only be a single <span title="concept-task">task</span>
    in the <span>event loop</span> at the next step, namely the task
    for the <code title="message-close">close</code> event. The
    "<span>terminate a worker</span>" algorithm removes all the
    events.</span></p>
-->

   </li>

   <li><p class="no-ja-translation" data-ja-hash="cfc4a3473c7cde1f5a4133c349682bab"><span class=en-original lang=en>If <var title="">worker global scope</var> is actually a
   <code><a href=#dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</a></code> object (i.e. the worker is
   a dedicated worker), then enable the <span>port message
   queue</span> of the worker's implicit port.</span></li>

   <li>

    <p class="no-ja-translation" data-ja-hash="ac8f871c5ad85c37527bc69c91141970"><span class=en-original lang=en><i title="">Event loop</i>: Wait until either there is a <span title=concept-task>task</span> in one of the <span>event
    loop</span>'s <span title="task queue">task queues</span> or <var title="">worker global scope</var>'s <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag is set
    to true.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="bcc803e78dd6f07ff20eaa1ca0d23303"><span class=en-original lang=en>Run the oldest task on one of the <span>event loop</span>'s
    <span title="task queue">task queues</span>, if any. The user
    agent may pick any <span>task queue</span>.</span></p>

    <p class="note no-ja-translation" data-ja-hash="2a401c207ed88f5206b2eb8a90fc91a6"><span class=en-original lang=en>The handling of events or the execution of
    callbacks might get prematurely aborted by the "<a href=#kill-a-worker>kill a
    worker</a>" or "<a href=#terminate-a-worker>terminate a worker</a>" algorithms
    defined below.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="0a62cf7225c4d215f05940236b695d05"><span class=en-original lang=en>Remove the task run in the previous step, if any, from its
    <span>task queue</span>.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="779764122a6b7c3177782cbb51d5c914"><span class=en-original lang=en>If there are any more events in the <span>event loop</span>'s
    <span title="task queue">task queues</span> or if <var title="">worker global scope</var>'s <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag is set
    to false, then jump back to the step above labeled <i>event
    loop</i>.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="fb906768fcbbd4867b29825a7893fe6e"><span class=en-original lang=en>If there are any outstanding transactions that have callbacks
    that involve <span title=concept-script>scripts</span> whose
    <span title="script's global object">global object</span> is the
    <var title="">worker global scope</var>, roll them back (without
    invoking any of the callbacks).</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="77a63b1af244b3bfda62ba8d7bf76ea9"><span class=en-original lang=en>Empty the <var title="">worker global scope</var>'s <span>list
    of active timeouts</span> and its <span>list of active
    intervals</span>.</span></p>

   </li>

<!-- v2-onclose
   <li>

    <p class="no-ja-translation" data-ja-hash="4cd03dfffdcf4808bf404c9bf5107eff"><span class=en-original lang=en>For each <code>Worker</code> or <code>SharedWorker</code>
    object associated with <var title="">worker global scope</var>,
    <span>queue a task</span> to <span>fire a simple event</span>
    called <code title="event-close">close</code> at that object.</span></p>

   </li>
-->
  </ol><hr><p class="no-ja-translation" data-ja-hash="cd7920afdad85f0228b3501a68536c9a"><span class=en-original lang=en>When a user agent is to <dfn id=kill-a-worker>kill a worker</dfn> it must
  run the following steps in parallel with the worker's main loop (the
  "<a href=#run-a-worker>run a worker</a>" processing model defined above):</span></p>

  <ol><!-- v2-onclose
   <li><p class="no-ja-translation" data-ja-hash="6806774d3d9a55fb29d85301b3552ad6"><span class=en-original lang=en>If the worker's <code>WorkerGlobalScope</code> object's
   <span title="dom-WorkerGlobalScope-closing">closing</span> flag is
   false, <span>queue a task</span> to <span>fire a simple
   event</span> called <code title="event-close">close</code> at the
   worker's <code>WorkerGlobalScope</code> object.</span></p></li>
--><li><p class="no-ja-translation" data-ja-hash="4cc11724db0ff9175e61747ac0b27285"><span class=en-original lang=en>Set the worker's <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object's <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag to
   true.</span></li>

<!-- v2-onclose
   <li><p class="no-ja-translation" data-ja-hash="4e3c7a6ff9a9f675020d75a10705eecc"><span class=en-original lang=en>Wait a user-agent-defined amount of time. If the "<span>run
   a worker</span>" processing model defined above immediately starts
   running event listeners registered for the <code
   title="event-close">close</code> event, this time should not be
   zero &mdash; the idea is that the <code
   title="event-close">close</code> event can be used to clean up
   when shutting down unexpectedly.</span></p></li>
-->

   <li><p class="no-ja-translation" data-ja-hash="09b4e752d892d358db0eb9f001f5a26c"><span class=en-original lang=en>If there are any <span title=concept-task>tasks</span>
   queued in the <span>event loop</span>'s <span title="task
   queue">task queues</span><!-- v2-onclose other than the <code
   title="event-close">close</code> event that this algorithm just
   added-->, discard them without processing them.</span></li>

<!-- v2-onclose
   <li><p class="no-ja-translation" data-ja-hash="f62a56e5aab0f0d08a9fa1e63f1983c5"><span class=en-original lang=en>If the <code title="event-close">close</code> event that
   this algorithm just queued hasn't yet been dispatched, then abort
   the script currently running in the worker.</span></p></li>
-->

   <li><p class="has-ja-translation" data-ja-hash="a53f0acde0e4a21781c4b31d5a0f110a"><span class=en-original lang=en>Wait a user-agent-defined amount of time.</span><span class=ja-translation lang=ja>利用者エージェント定義の時間、待ちます。</span></li>

   <li><p class="no-ja-translation" data-ja-hash="fbb7fecc04423fb209634e5473bd7ec1"><span class=en-original lang=en>Abort the script currently running in the worker<!--
   v2-onclose (if any script is running, then it will be a handler for
   the <code title="event-close">close</code> event)-->.</span></li>

  </ol><p class="no-ja-translation" data-ja-hash="065b6253058d6c118693257b76ed3444"><span class=en-original lang=en>User agents may invoke the "<a href=#kill-a-worker>kill a worker</a>"
  processing model on a worker at any time, e.g. in response to user
  requests, in response to CPU quota management, or when a worker
  stops being an <a href=#active-needed-worker>active needed worker</a> if the worker
  continues executing even after its <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag was
  set to true.</span></p>

  <hr><p class="no-ja-translation" data-ja-hash="af2a7479f3a6fc4f418bd8e7255c63be"><span class=en-original lang=en>When a user agent is to <dfn id=terminate-a-worker>terminate a worker</dfn> it must run
  the following steps in parallel with the worker's main loop (the
  "<a href=#run-a-worker>run a worker</a>" processing model defined above):</span></p>

  <ol><li><p class="no-ja-translation" data-ja-hash="4cc11724db0ff9175e61747ac0b27285"><span class=en-original lang=en>Set the worker's <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object's
   <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag to
   true.</span></li>

   <li><p class="no-ja-translation" data-ja-hash="a9cf50df3de2e3788a3125ace8cf61f5"><span class=en-original lang=en>If there are any <span title=concept-task>tasks</span>
   queued in the <span>event loop</span>'s <span title="task
   queue">task queues</span>, discard them without processing
   them.</span></li>

   <li><p class="has-ja-translation" data-ja-hash="fcb471f3c8cace3a86095dcb29d25515"><span class=en-original lang=en>Abort the script currently running in the worker.</span><span class=ja-translation lang=ja>労働者中で現在走っているスクリプトを停止します。</span></li>

   <li><p class="no-ja-translation" data-ja-hash="533246b74ff40190332c8ca473d635b5"><span class=en-original lang=en>If the worker's <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object is
   actually a <code><a href=#dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</a></code> object (i.e. the
   worker is a dedicated worker), then empty the <span>port message
   queue</span> of the port that the worker's implicit port is
   entangled with.</span></li>

  </ol><hr><p class="no-ja-translation" data-ja-hash="232ca3945fb57a3baa9cc0675ff99caa"><span class=en-original lang=en>The <span>task source</span> for the tasks mentioned above is the
  <span>DOM manipulation task source</span>.</span></p>


  <h3 id=runtime-script-errors class="has-ja-translation" data-ja-hash="eb260f04266c3b94080b5c3f88c55a31"><span class=en-original lang=en><span class=secno>4.7 </span>Runtime script errors</span><span class=ja-translation lang=ja><span class=secno>4.7 </span>実行時スクリプト誤り</span></h3>

  <p class="no-ja-translation" data-ja-hash="7bd3f1cdf85033908e9608a3f27fc9d1"><span class=en-original lang=en>Whenever an uncaught runtime script error occurs in one of the
  worker's scripts, if the error did not occur while handling a
  previous script error, the user agent must <span>report the
  error</span> using the <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object's <code title=handler-WorkerGlobalScope-onerror><a href=#handler-workerglobalscope-onerror>onerror</a></code>
  attribute. <a href=#refsHTML5>[HTML5]</a></span></p>

  <p class="no-ja-translation" data-ja-hash="1d4d18d12610442bca7072503caba230"><span class=en-original lang=en>For shared workers, if the error is still <i title=concept-error-nothandled>not handled</i> afterwards, or if
  the error occurred while handling a previous script error, the error
  should be reported to the user. <a href=#refsHTML5>[HTML5]</a></span></p>

  <p class="no-ja-translation" data-ja-hash="44fbeda15b001a0dc82fe40089bb81bb"><span class=en-original lang=en>For dedicated workers, if the error is still <i title=concept-error-nothandled>not handled</i> afterwards, or if
  the error occurred while handling a previous script error, the user
  agent must <span>queue a task</span> to <a href=#fire-a-worker-error-event>fire a worker error
  event</a> at the <code><a href=#worker>Worker</a></code> object associated with the
  worker.</span></p>

  <p class="no-ja-translation" data-ja-hash="c96676fcc4ab90893eca070f70c76249"><span class=en-original lang=en>When the user agent is to <dfn id=fire-a-worker-error-event>fire a worker error event</dfn> at
  a <code><a href=#worker>Worker</a></code> object, it must dispatch an event that uses
  the <code><a href=#errorevent>ErrorEvent</a></code> interface, with the name <code title=event-error>error</code>, that doesn't bubble and is
  cancelable, with its <code title=dom-ErrorEvent-message><a href=#dom-errorevent-message>message</a></code>, <code title=dom-ErrorEvent-filename><a href=#dom-errorevent-filename>filename</a></code>, and <code title=dom-ErrorEvent-lineno><a href=#dom-errorevent-lineno>lineno</a></code> attributes set
  appropriately. The default action of this event depends on whether
  the <code><a href=#worker>Worker</a></code> object is itself in a worker. If it is, and
  that worker is also a dedicated worker, then the user agent must
  again <span>queue a task</span> to <a href=#fire-a-worker-error-event>fire a worker error
  event</a> at the <code><a href=#worker>Worker</a></code> object associated with
  <em>that</em> worker. Otherwise, then the error should be reported
  to the user.</span></p>

  <p class="no-ja-translation" data-ja-hash="232ca3945fb57a3baa9cc0675ff99caa"><span class=en-original lang=en>The <span>task source</span> for the tasks mentioned above is the
  <span>DOM manipulation task source</span>.</span></p>

  <hr><pre class="idl no-ja-translation" data-ja-hash="75e1a0de2be298c9db36c73510aae01d"><span class=en-original lang=en>interface <dfn id=errorevent>ErrorEvent</dfn> : Event {
  readonly attribute DOMString <a href=#dom-errorevent-message title=dom-ErrorEvent-message>message</a>;
  readonly attribute DOMString <a href=#dom-errorevent-filename title=dom-ErrorEvent-filename>filename</a>;
  readonly attribute unsigned long <a href=#dom-errorevent-lineno title=dom-ErrorEvent-lineno>lineno</a>;
  void <a href=#dom-errorevent-initerrorevent title=dom-ErrorEvent-initErrorEvent>initErrorEvent</a>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMString messageArg, in DOMString filenameArg, in unsigned long linenoArg);
  void <a href=#dom-errorevent-initerroreventns title=dom-ErrorEvent-initErrorEventNS>initErrorEventNS</a>(in DOMString namespaceURIArg, in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMString messageArg, in DOMString filenameArg, in unsigned long linenoArg);
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="741eed0816bcef0dfb1fed290dc14c9c"><span class=en-original lang=en>The <dfn id=dom-errorevent-initerrorevent title=dom-ErrorEvent-initErrorEvent><code>initErrorEvent()</code></dfn>
  and <dfn id=dom-errorevent-initerroreventns title=dom-ErrorEvent-initErrorEventNS><code>initErrorEventNS()</code></dfn>
  methods must initialize the event in a manner analogous to the
  similarly-named methods in the DOM Events interfaces. <a href=#refsDOMEVENTS>[DOMEVENTS]</a></span></p>

  <p class="no-ja-translation" data-ja-hash="c3d08d500554faa699d875e3015209b9"><span class=en-original lang=en>The <dfn id=dom-errorevent-message title=dom-ErrorEvent-message><code>message</code></dfn>
  attribute represents the error message.</span></p>

  <p class="no-ja-translation" data-ja-hash="27affe597e932e64fc4db85fad27e91b"><span class=en-original lang=en>The <dfn id=dom-errorevent-filename title=dom-ErrorEvent-filename><code>filename</code></dfn>
  attribute represents the <span>absolute URL</span> of the script in
  which the error originally occurred.</span></p>

  <p class="no-ja-translation" data-ja-hash="4322851b5483408bad81570533bf6251"><span class=en-original lang=en>The <dfn id=dom-errorevent-lineno title=dom-ErrorEvent-lineno><code>lineno</code></dfn>
  attribute represents the line number where the error occurred in the
  script.</span></p>


  <h3 id=creating-workers class="has-ja-translation" data-ja-hash="f0a4732d38d01e3d103b68468f9fe234"><span class=en-original lang=en><span class=secno>4.8 </span>Creating workers</span><span class=ja-translation lang=ja><span class=secno>4.8 </span>労働者の作成</span></h3>

  <h4 id=the-abstractworker-abstract-interface class="has-ja-translation" data-ja-hash="fe5227371e801f4ac588d0d07472a900" data-ja-real-hash="fea226dea005bb8238586cd20b34aa2f"><span class=en-original lang=en><span class=secno>4.8.1 </span>The <code><a href=#abstractworker>AbstractWorker</a></code> abstract interface</span><span class=ja-translation lang=ja><span class=secno>4.8.1 </span><code><a href=#abstractworker>AbstractWorker</a></code> 抽象界面</span></h4>

  <pre class="idl no-ja-translation" data-ja-hash="84c84199da6cc07390dbf49ed3f9a34c"><span class=en-original lang=en>interface <dfn id=abstractworker>AbstractWorker</dfn> {
           attribute <span>Function</span> <a href=#handler-abstractworker-onerror title=handler-AbstractWorker-onerror>onerror</a>;
<!-- v2-onclose           attribute <span>Function</span> <span title="handler-AbstractWorker-onclose">onclose</span>; -->
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="b6a7afc5ececf4988bace69746cd2a40"><span class=en-original lang=en>Objects implementing the <code><a href=#abstractworker>AbstractWorker</a></code> interface
  must also implement the <code>EventTarget</code> interface.</span></p>

  <p class="no-ja-translation" data-ja-hash="591ccc34c3069aed8870829263c9ad82"><span class=en-original lang=en>The following are the <span>event handler attributes</span> (and their corresponding <span title="event handler event type">event handler event types</span>)
  that must be supported, as IDL attributes, by objects implementing
  the <code><a href=#abstractworker>AbstractWorker</a></code> interface:</span></p>

  <table><thead><tr><th class="no-ja-translation" data-ja-hash="c85726f0c6ba202006ec1f912e68aa76"><span class=en-original lang=en><span title="event handler attributes">event handler attribute</span> </span><th class="no-ja-translation" data-ja-hash="3fc98eebba71602c62d8b2fd74645dc9"><span class=en-original lang=en><span>Event handler event type</span>
   </span><tbody><tr><td class="no-ja-translation" data-ja-hash="797655c7ba76af81be91c1f52bf92e5d"><span class=en-original lang=en><dfn id=handler-abstractworker-onerror title=handler-AbstractWorker-onerror><code>onerror</code></dfn> </span><td class="no-ja-translation" data-ja-hash="bf1b78c16e7c3a3de662d83f487bffff"><span class=en-original lang=en> <code title=event-error>error</code>
<!-- v2-onclose    --></span><!--<tr><td class="no-ja-translation" data-ja-hash="5bacdeaff60366f7971634c5de89cc1a"><span class=en-original lang=en><dfn title="handler-AbstractWorker-onclose"><code>onclose</code></dfn> </span><td class="no-ja-translation" data-ja-hash="e899358e829911a25c083ed9bc6519e6"><span class=en-original lang=en> <code title="event-close">close</code> -->
  </span></table><h4 id=dedicated-workers-and-the-worker-interface class="no-ja-translation" data-ja-hash="4d0010617afd55731512f81d11e29921"><span class=en-original lang=en><span class=secno>4.8.2 </span>Dedicated workers and the <code><a href=#worker>Worker</a></code> interface</span></h4>

  <pre class="idl no-ja-translation" data-ja-hash="d3ff732dd43e4f43a4fe39374e4b65ae"><span class=en-original lang=en>[<a href=#dom-worker title=dom-Worker>Constructor</a>(in DOMString scriptURL)]
interface <dfn id=worker>Worker</dfn> : <a href=#abstractworker>AbstractWorker</a> {
  void <a href=#dom-worker-terminate title=dom-Worker-terminate>terminate</a>();

  void <a href=#dom-worker-postmessage title=dom-Worker-postMessage>postMessage</a>(in any message, optional in <span>MessagePortArray</span> ports);<!--
  <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
           attribute <span>Function</span> <a href=#handler-worker-onmessage title=handler-Worker-onmessage>onmessage</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="c01e50cb895f4eaa527128e73934b76c"><span class=en-original lang=en>The <dfn id=dom-worker-terminate title=dom-Worker-terminate><code>terminate()</code></dfn> method,
  when invoked, must cause the "<a href=#terminate-a-worker>terminate a worker</a>"
  algorithm to be run on the worker with with the object is
  associated.</span></p>

  <p class="no-ja-translation" data-ja-hash="f306158a0574a5376130b398642a9bc3"><span class=en-original lang=en><code><a href=#worker>Worker</a></code> objects act as if they had an implicit
  <code>MessagePort</code> associated with them. This port is part of
  a channel that is set up when the worker is created, but it is not
  exposed. This object must never be garbage collected before the
  <code><a href=#worker>Worker</a></code> object.</span></p>

  <p class="no-ja-translation" data-ja-hash="3347b0248a16085b3e8a073aed81f1d8"><span class=en-original lang=en>All messages received by that port must immediately be retargeted
  at the <code><a href=#worker>Worker</a></code> object.</span></p>

  <p class="no-ja-translation" data-ja-hash="58e82dfd8fd30e4340d6d1f7f7a08239"><span class=en-original lang=en>The <dfn id=dom-worker-postmessage title=dom-Worker-postMessage><code>postMessage()</code></dfn><!--
  and <dfn
  title="dom-Worker-startConversation"><code>startConversation()</code></dfn>-->
  method<!--s (startConversation)--> on <code><a href=#worker>Worker</a></code> objects
  must act as if, when invoked, it<!--/they (startConversation)-->
  immediately invoked the method of the same name on the port, with
  the same arguments, and returned the same return value.</span></p>

  <p class="no-ja-translation" data-ja-hash="8ba86d15e8d2d8bd7427e8e4dcfbd208"><span class=en-original lang=en>The following are the <span>event handler attributes</span> (and their corresponding <span title="event handler event type">event handler event types</span>)
  that must be supported, as IDL attributes, by objects implementing
  the <code><a href=#worker>Worker</a></code> interface:</span></p>

  <table><thead><tr><th class="no-ja-translation" data-ja-hash="c85726f0c6ba202006ec1f912e68aa76"><span class=en-original lang=en><span title="event handler attributes">event handler attribute</span> </span><th class="no-ja-translation" data-ja-hash="3fc98eebba71602c62d8b2fd74645dc9"><span class=en-original lang=en><span>Event handler event type</span>
   </span><tbody><tr><td class="no-ja-translation" data-ja-hash="936f67c1111af9460db35858624e3ce9"><span class=en-original lang=en><dfn id=handler-worker-onmessage title=handler-Worker-onmessage><code>onmessage</code></dfn> </span><td class="no-ja-translation" data-ja-hash="fe07e2527bf13c457386ab4807af84a0"><span class=en-original lang=en> <code title=event-message>message</code>
  </span></table><hr><p class="no-ja-translation" data-ja-hash="071022f5c10c547e44e7e3a998659333"><span class=en-original lang=en>When the <dfn id=dom-worker title=dom-Worker><code>Worker(<var title="">scriptURL</var>)</code></dfn> constructor is invoked, the
  user agent must run the following steps:</span></p>

  <ol><li><p class="no-ja-translation" data-ja-hash="2ca4870c8239974ba241fd037e090c44"><span class=en-original lang=en><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument relative to the <span>first
   script</span>'s <span title="script's base URL">base URL</span>,
   when the method is invoked.</span></li>

   <li><p class="has-ja-translation" data-ja-hash="160444b5a61c1e71f39825a01936237f"><span class=en-original lang=en>If this fails, throw a <code>SYNTAX_ERR</code>
   exception.</span><span class=ja-translation lang=ja>これが失敗した場合、 <code>SYNTAX_ERR</code>
例外を投げます。</span></li>

   <li>

    <p class="no-ja-translation" data-ja-hash="8c1bc8b7160649d18a3c7780560d2b6d"><span class=en-original lang=en>If the <span>origin</span> of the resulting <span>absolute
    URL</span> is not the <span title="same origin">same</span> as the
    origin of the <span title=concept-script>script</span> that
    invoked the constructor, then throw a <span>security
    exception</span>.</span></p>

    <p class="note no-ja-translation" data-ja-hash="70778ef58116d00717c7dad6522d3d5b"><span class=en-original lang=en>Thus, scripts must be external files with the same
    scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
    URL, and a <code>https:</code> page couldn't start workers using
    scripts with <code>http:</code> URLs.</span></p>

   </li>

   <li><p class="no-ja-translation" data-ja-hash="b5bddf55144f8b1ff3c2a755b8ada3e0"><span class=en-original lang=en><span>Create a new <code><a href=#dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</a></code>
   object</span>. Let <var title="">worker global scope</var> be this
   new object.</span></li>

   <li><p class="no-ja-translation" data-ja-hash="5f11902e2367f64698f9d31e03a9d235"><span class=en-original lang=en>Create a new <code><a href=#worker>Worker</a></code> object, associated with
   <var title="">worker global scope</var>. Let <var title="">worker</var> be this new object.</span></li>

   <li><p class="no-ja-translation" data-ja-hash="7b066bb31c499860c38db05cac15b6b9"><span class=en-original lang=en><span>Create a <code>MessagePort</code> object</span> owned
   by the <span title="script's global scope">global scope</span> of
   the <span title=concept-script>script</span> that invoked the
   constructor. Let this be the <var title="">outside
   port</var>.</span></li>

   <li><p class="has-ja-translation" data-ja-hash="91024eaaebdc23ea683ace1b3e316962"><span class=en-original lang=en>Associate the <var title="">outside port</var> with <var title="">worker</var>.</span><span class=ja-translation lang=ja><var title="">outside port</var> を <var
     title="">worker</var> に関連付けます。</span></li>

   <li><p class="no-ja-translation" data-ja-hash="2d1b035dbaad3feca57eb124d161b034"><span class=en-original lang=en><span>Create a <code>MessagePort</code> object</span> owned
   by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</span></li>

   <li><p class="no-ja-translation" data-ja-hash="c7df111ebbfeab4bffdbe80d19fdb0ba"><span class=en-original lang=en>Associate <var title="">inside port</var> with <var title="">worker global scope</var>.</span></li>

   <li><p class="no-ja-translation" data-ja-hash="bf2642ced659847cb4402165d2ab3a8e"><span class=en-original lang=en><span>Entangle</span> <var title="">outside port</var> and
   <var title="">inside port</var>.</span></li>

   <li><p class="has-ja-translation" data-ja-hash="2c5bd80faeda34c67a2533f32a477c51"><span class=en-original lang=en>Return <var title="">worker</var>, and run the following
   steps asynchronously.</span><span class=ja-translation lang=ja><var title="">worker</var> を返し、以降の段階を非同期に走らせます。</span></li>

   <li><p class="no-ja-translation" data-ja-hash="486f13bccfc4521d81f95f8a83a34838"><span class=en-original lang=en>Enable <var title="">inside port</var>'s <span>port message
   queue</span>.</span></li>

   <li><p class="no-ja-translation" data-ja-hash="f226f14fb6f714ae0ebb2e1d19b80cb0"><span class=en-original lang=en>Enable <var title="">outside port</var>'s <span>port message
   queue</span>.</span></li>

   <li>

    <p class="no-ja-translation" data-ja-hash="55e6e7d35bf5d3d20aefe01d055f5e6b"><span class=en-original lang=en>Let <var title="">docs</var> be the <a href=#list-of-relevant-document-objects-to-add>list of relevant
    <code>Document</code> objects to add</a> given the <span title="script's global scope">global scope</span> of the <span title=concept-script>script</span> that invoked the
    constructor.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="55e64a61fc96598db79195cddb4bb2f9"><span class=en-original lang=en><a href="#add-a-document-to-the-worker's-documents" title="add a document to the worker's documents">Add to
    <var title="">worker global scope</var>'s list of <span>the
    worker's <code>Document</code>s</span></a> the
    <code>Document</code> objects in <var title="">docs</var>.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="7c3d95cd57d78baee3024bef7b2b71f6"><span class=en-original lang=en>If the <span title="script's global scope">global scope</span>
    of the <span title=concept-script>script</span> that invoked the
    constructor is a <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object (i.e. we
    are creating a nested worker), add <var title="">worker global
    scope</var> to the list of <a href="#the-worker's-workers">the worker's workers</a> of the
    <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object that is the <span title="script's global scope">global scope</span> of the <span title=concept-script>script</span> that invoked the
    constructor.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="8d52f75615bdf14ecca1950ce2fe376b"><span class=en-original lang=en><a href=#run-a-worker>Run a worker</a> for the resulting <span>absolute
    URL</span>, with the <span>script browsing context</span> of the
    script that invoked the method as the <var title="">owner browsing
    context</var>, and with <var title="">worker global scope</var> as
    the global scope.</span></p>

   </li>

  </ol><p class="no-ja-translation" data-ja-hash="62d6758eaf2020c4112ab186636f4f33"><span class=en-original lang=en>This constructor must be visible when the <span>script's global
  scope</span> is either a <code>Window</code> object or an object
  implementing the <code><a href=#workerutils>WorkerUtils</a></code> interface.</span></p>


  <h4 id=shared-workers-and-the-sharedworker-interface class="no-ja-translation" data-ja-hash="3b77b75af8223662d0137a2dd84957ab"><span class=en-original lang=en><span class=secno>4.8.3 </span>Shared workers and the <code><a href=#sharedworker>SharedWorker</a></code> interface</span></h4>

  <pre class="idl no-ja-translation" data-ja-hash="962f28d14d6fa9ffaf136b8699349763"><span class=en-original lang=en>[<a href=#dom-sharedworker title=dom-SharedWorker>Constructor</a>(in DOMString scriptURL, optional in DOMString name)]
interface <dfn id=sharedworker>SharedWorker</dfn> : <a href=#abstractworker>AbstractWorker</a> {
  readonly attribute <span>MessagePort</span> <a href=#dom-sharedworker-port title=dom-SharedWorker-port>port</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="5cf4affd83f6594d8f8bc1a32f68ab35"><span class=en-original lang=en>The <dfn id=dom-sharedworker-port title=dom-SharedWorker-port><code>port</code></dfn>
  attribute must return the value it was assigned by the object's
  constructor. It represents the <code>MessagePort</code> for
  communicating with the shared worker.</span></p>

  <p class="no-ja-translation" data-ja-hash="a0ab2a2723152011df53c0fc544b493b"><span class=en-original lang=en>When the <dfn id=dom-sharedworker title=dom-SharedWorker><code>SharedWorker(<var title="">scriptURL</var>, <var title="">name</var>)</code></dfn>
  constructor is invoked, the user agent must run the following
  steps:</span></p>

  <ol><li><p class="has-ja-translation" data-ja-hash="3219e42f1040482201a693e248f580cb"><span class=en-original lang=en><span title="resolve a url">Resolve</span> the <var title="">scriptURL</var> argument.</span><span class=ja-translation lang=ja><var
     title="">scriptURL</var> 引数を<span title="resolve a url">解決</span>します。</span></li>

   <li><p class="has-ja-translation" data-ja-hash="160444b5a61c1e71f39825a01936237f"><span class=en-original lang=en>If this fails, throw a <code>SYNTAX_ERR</code>
   exception.</span><span class=ja-translation lang=ja>これが失敗した場合、 <code>SYNTAX_ERR</code>
例外を投げます。</span></li>

   <li><p class="no-ja-translation" data-ja-hash="a0b3d695bae7e2ce874ab6966d7aa86b"><span class=en-original lang=en>Otherwise, let <var title="">scriptURL</var> be the
   resulting <span>absolute URL</span>.</span></li>

   <li><p class="no-ja-translation" data-ja-hash="8a0ad4f3e4cdc7bb4c8643040fc02e97"><span class=en-original lang=en>Let <var title="">name</var> be the value of the second
   argument, or the empty string if the second argument was
   omitted.</span></li>

   <li>

    <p class="no-ja-translation" data-ja-hash="c584325143c8f3315c46007144a86641"><span class=en-original lang=en>If the <span>origin</span> of <var title="">scriptURL</var> is
    not the <span title="same origin">same</span> as the origin of the
    script that invoked the constructor, then throw a <span>security
    exception</span>.</span></p>

    <p class="note no-ja-translation" data-ja-hash="70778ef58116d00717c7dad6522d3d5b"><span class=en-original lang=en>Thus, scripts must be external files with the same
    scheme as the original page: you can't load a script from a <code title="">data:</code> URL or <code title="">javascript:</code>
    URL, and a <code>https:</code> page couldn't start workers using
    scripts with <code>http:</code> URLs.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="55e6e7d35bf5d3d20aefe01d055f5e6b"><span class=en-original lang=en>Let <var title="">docs</var> be the <a href=#list-of-relevant-document-objects-to-add>list of relevant
    <code>Document</code> objects to add</a> given the <span title="script's global scope">global scope</span> of the <span title=concept-script>script</span> that invoked the
    constructor.</span></p>

   </li>

   <li>

    <p class="has-ja-translation" data-ja-hash="683a2c0080e014b9eae98b884ccaf7e4"><span class=en-original lang=en>Execute the following substeps atomically:</span><span class=ja-translation lang=ja>次の部分段階群を原子的に実行します。</span></p>

    <ol><li><p class="no-ja-translation" data-ja-hash="b38ef0f6a7b346d45c984332a0b8776d"><span class=en-original lang=en>Create a new <code><a href=#sharedworker>SharedWorker</a></code> object, which will
     shortly be associated with a <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code>
     object. Let this <code><a href=#sharedworker>SharedWorker</a></code> object be <var title="">worker</var>.</span></li>

     <li><p class="no-ja-translation" data-ja-hash="629bd7f10d8162f8dbf21128830192dc"><span class=en-original lang=en><span>Create a <code>MessagePort</code> object</span>
     owned by the <span title="script's global scope">global
     scope</span> of the script that invoked the method. Let this be
     the <var title="">outside port</var>.</span></li>

     <li><p class="no-ja-translation" data-ja-hash="2945bc791092fa6a9100ef8df34f4c10"><span class=en-original lang=en>Assign <var title="">outside port</var> to the <code title=dom-SharedWorker-port><a href=#dom-sharedworker-port>port</a></code> attribute of <var title="">worker</var>.</span></li>

     <li><p class="no-ja-translation" data-ja-hash="bf1807a565bd680ac1131e8903499e6c"><span class=en-original lang=en>Let <var title="">worker global scope</var> be
     null.</span></li>

     <li><p class="no-ja-translation" data-ja-hash="48d19fa2bb17053a97267718abc71c9f"><span class=en-original lang=en>If <var title="">name</var> is not the empty string and
     there exists a <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code> object whose
     <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a> flag
     is false, whose <code title=dom-WorkerGlobalScope-name>name</code> attribute is
     exactly equal to <var title="">name</var>, and whose <code title=dom-WorkerGlobalScope-location><a href=#dom-workerglobalscope-location>location</a></code> attribute
     represents an <span>absolute URL</span> with the <span>same
     origin</span> as <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
     <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code> object.</span></li>

     <li><p class="no-ja-translation" data-ja-hash="5f0ebd0b17c71f870fff82e13aa4d49f"><span class=en-original lang=en>Otherwise, if <var title="">name</var> is the empty string
     and there exists a <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code> object
     whose <a href=#dom-workerglobalscope-closing title=dom-WorkerGlobalScope-closing>closing</a>
     flag is false, and whose <code title=dom-WorkerGlobalScope-location><a href=#dom-workerglobalscope-location>location</a></code> attribute
     is exactly equal to <var title="">scriptURL</var>, then let <var title="">worker global scope</var> be that
     <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code> object.</span></li>

     <li>

      <p class="no-ja-translation" data-ja-hash="f49b52bc5df237a2451163ce09a7d8b0"><span class=en-original lang=en>If <var title="">worker global scope</var> is not null, then
      run these steps:</span></p>

      <ol><li><p class="no-ja-translation" data-ja-hash="c93c344ad574dd1e037e0c9fd4bdbc24"><span class=en-original lang=en>If <var title="">worker global scope</var>'s <code title=dom-WorkerGlobalScope-location><a href=#dom-workerglobalscope-location>location</a></code>
       attribute represents an <span>absolute URL</span> that is not
       exactly equal to <var title="">scriptURL</var>, then throw a
       <code>URL_MISMATCH_ERR</code> exception and abort all these
       steps.</span></li>

       <li><p class="has-ja-translation" data-ja-hash="9c4f87efaa1e868cd6bf63dbffa749c0"><span class=en-original lang=en>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</span><span class=ja-translation lang=ja><var title="">worker</var> を <var title="">worker
         global scope</var> に関連付けます。</span></li>

       <li><p class="no-ja-translation" data-ja-hash="bab9c8cea075e0f3614c731f09b49892"><span class=en-original lang=en><span>Create a <code>MessagePort</code> object</span>
       owned by <var title="">worker global scope</var>. Let this
       be the <var title="">inside port</var>.</span></li>

       <li><p class="no-ja-translation" data-ja-hash="bf2642ced659847cb4402165d2ab3a8e"><span class=en-original lang=en><span>Entangle</span> <var title="">outside port</var>
       and <var title="">inside port</var>.</span></li>

       <li><p class="has-ja-translation" data-ja-hash="ebb713e9e29aab450d79b533c42b67ae"><span class=en-original lang=en>Return <var title="">worker</var> and perform the next
       step asynchronously.</span><span class=ja-translation lang=ja><var title="">worker</var> を返し、
次の段階を非同期に実行します。</span></li>

       <li><p class="no-ja-translation" data-ja-hash="54fc802e5e886ae34c575b12f00dfb03"><span class=en-original lang=en>Create an event that uses the <code>MessageEvent</code>
       interface, with the name <code title=event-connect>connect</code>, which does not bubble, is
       not cancelable, has no default action, has a <code title=dom-MessageEvent-data>data</code> attribute whose value
       is the empty string and has a <code title=dom-MessageEvent-ports>ports</code> attribute whose
       value is an array containing only the newly created port, and
       <span>queue a task</span> to dispatch the event at <var title="">worker global scope</var>.</span></li>

       <li>

        <p class="no-ja-translation" data-ja-hash="55e64a61fc96598db79195cddb4bb2f9"><span class=en-original lang=en><a href="#add-a-document-to-the-worker's-documents" title="add a document to the worker's documents">Add to
        <var title="">worker global scope</var>'s list of <span>the
        worker's <code>Document</code>s</span></a> the
        <code>Document</code> objects in <var title="">docs</var>.</span></p>

       </li>

       <li>

        <p class="no-ja-translation" data-ja-hash="71e9b593868deeebab7e077539f42964"><span class=en-original lang=en>If the <span title="script's global scope">global
        scope</span> of the <span title=concept-script>script</span>
        that invoked the constructor is a
        <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object, add <var title="">worker global scope</var> to the list of <a href="#the-worker's-workers">the
        worker's workers</a> of the <code><a href=#workerglobalscope>WorkerGlobalScope</a></code>
        object that is the <span title="script's global scope">global
        scope</span> of the <span title=concept-script>script</span>
        that invoked the constructor.</span></p>

       </li>

       <li><p class="has-ja-translation" data-ja-hash="dd866391287c967d4799df78a7249911"><span class=en-original lang=en>Abort all these steps.</span><span class=ja-translation lang=ja>これらの段階をすべて停止します。</span></li>

      </ol></li>

     <li><p class="no-ja-translation" data-ja-hash="08b38f99ab8a1b8451edf6d12f8f60d9"><span class=en-original lang=en><span>Create a new <code><a href=#sharedworkerglobalscope>SharedWorkerGlobalScope</a></code>
     object</span>. Let <var title="">worker global scope</var> be
     this new object.</span></li>

     <li><p class="has-ja-translation" data-ja-hash="9c4f87efaa1e868cd6bf63dbffa749c0"><span class=en-original lang=en>Associate <var title="">worker</var> with <var title="">worker global scope</var>.</span><span class=ja-translation lang=ja><var title="">worker</var> を <var title="">worker
         global scope</var> に関連付けます。</span></li>

     <li><p class="no-ja-translation" data-ja-hash="5197138b23b238d1ca44cd6260532c5d"><span class=en-original lang=en>Set the <code title=dom-SharedWorkerGlobalScope-name><a href=#dom-sharedworkerglobalscope-name>name</a></code> attribute of
     <var title="">worker global scope</var> to <var title="">name</var>.</span></li>

     <li><p class="no-ja-translation" data-ja-hash="2d1b035dbaad3feca57eb124d161b034"><span class=en-original lang=en><span>Create a <code>MessagePort</code> object</span>
     owned by <var title="">worker global scope</var>. Let <var title="">inside port</var> be this new object.</span></li>

     <li><p class="no-ja-translation" data-ja-hash="bf2642ced659847cb4402165d2ab3a8e"><span class=en-original lang=en><span>Entangle</span> <var title="">outside port</var> and
     <var title="">inside port</var>.</span></li>

    </ol></li>

   <li><p class="no-ja-translation" data-ja-hash="8383fd384ab33b4860228f2c27483044"><span class=en-original lang=en>Return <var title="">worker</var> and perform the remaining
   steps asynchronously.</span></li>

   <li><p class="no-ja-translation" data-ja-hash="54fc802e5e886ae34c575b12f00dfb03"><span class=en-original lang=en>Create an event that uses the <code>MessageEvent</code>
   interface, with the name <code title=event-connect>connect</code>, which does not bubble, is not
   cancelable, has no default action, has a <code title=dom-MessageEvent-data>data</code> attribute whose value is
   the empty string and has a <code title=dom-MessageEvent-ports>ports</code> attribute whose value
   is an array containing only the newly created port, and <span>queue
   a task</span> to dispatch the event at <var title="">worker global
   scope</var>.</span></li>

   <li>

    <p class="no-ja-translation" data-ja-hash="55e64a61fc96598db79195cddb4bb2f9"><span class=en-original lang=en><a href="#add-a-document-to-the-worker's-documents" title="add a document to the worker's documents">Add to
    <var title="">worker global scope</var>'s list of <span>the
    worker's <code>Document</code>s</span></a> the
    <code>Document</code> objects in <var title="">docs</var>.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="71e9b593868deeebab7e077539f42964"><span class=en-original lang=en>If the <span title="script's global scope">global scope</span>
    of the <span title=concept-script>script</span> that invoked the
    constructor is a <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object, add <var title="">worker global scope</var> to the list of <a href="#the-worker's-workers">the
    worker's workers</a> of the <code><a href=#workerglobalscope>WorkerGlobalScope</a></code>
    object that is the <span title="script's global scope">global
    scope</span> of the <span title=concept-script>script</span>
    that invoked the constructor.</span></p>

   </li>

   <li>

    <p class="no-ja-translation" data-ja-hash="ede1af9701af46611248c5c973f31cde"><span class=en-original lang=en><a href=#run-a-worker>Run a worker</a> for <var title="">scriptURL</var>,
    with the <span>script browsing context</span> of the script that
    invoked the method as the <var title="">owner browsing
    context</var>, and with <var title="">worker global scope</var> as
    the global scope.</span></p>

   </li>

  </ol><p class="no-ja-translation" data-ja-hash="62d6758eaf2020c4112ab186636f4f33"><span class=en-original lang=en>This constructor must be visible when the <span>script's global
  scope</span> is either a <code>Window</code> object or an object
  implementing the <code><a href=#workerutils>WorkerUtils</a></code> interface.</span></p>

  <p class="no-ja-translation" data-ja-hash="232ca3945fb57a3baa9cc0675ff99caa"><span class=en-original lang=en>The <span>task source</span> for the tasks mentioned above is the
  <span>DOM manipulation task source</span>.</span></p>


  <h2 id=apis-available-to-workers class="has-ja-translation" data-ja-hash="4fce100e6a2eccbb2df8631a438feeb6"><span class=en-original lang=en><span class=secno>5 </span>APIs available to workers</span><span class=ja-translation lang=ja><span class=secno>5 </span>労働者が利用可能な API</span></h2>

  <pre class="idl no-ja-translation" data-ja-hash="eb360baf4cea0845dd1f29248fa6057f"><span class=en-original lang=en>[Supplemental, NoInterfaceObject]
interface <dfn id=workerutils>WorkerUtils</dfn> {
  void <a href=#dom-workerglobalscope-importscripts title=dom-WorkerGlobalScope-importScripts>importScripts</a>(in DOMString... urls);
  readonly attribute <a href=#worker-navigator title=worker-Navigator>Navigator</a> <a href=#dom-worker-navigator title=dom-worker-navigator>navigator</a>;
};
// implemented by <a href=#workerglobalscope>WorkerGlobalScope</a></span></pre>

  <p class="has-ja-translation" data-ja-hash="fc1e0d30e2c0869e54fb2487a7dd6836" data-ja-real-hash="a9f04ef5503be39e966b5cc5744a3d1c"><span class=en-original lang=en>Objects that implement the <code><a href=#workerglobalscope>WorkerGlobalScope</a></code>
  interface must also implement the <code><a href=#workerutils>WorkerUtils</a></code>
  interface.</span><span class=ja-translation lang=ja><code><a href=#workerglobalscope>WorkerGlobalScope</a></code> 界面を実装するオブジェクトは、 <code><a href=#workerutils>WorkerUtils</a></code> 界面も実装しなければ<em class=rfc2119 title="MUST">なりません</em>。</span></p>

  <p class="no-ja-translation" data-ja-hash="66c8457f878286e5a4ecb06e2d847359"><span class=en-original lang=en>Objects that implement the <code><a href=#workerutils>WorkerUtils</a></code> interface
  must also implement the <code>WindowTimers</code> interface. (This
  interface provides the <code title="">setTimeout()</code> method and
  its friends.)</span></p><!-- XXX ref -->

  <!-- XXX ApplicationCache -->

  <!-- XXX debugging: void log(in DOMString s); // log to console -->

  <hr><p class="has-ja-translation" data-ja-hash="59b28734296c1cd390d156b0e8e5fb94"><span class=en-original lang=en>The DOM APIs (<code>Node</code> objects, <code>Document</code>
  objects, etc) are not available to workers in this version of this
  specification.</span><span class=ja-translation lang=ja>DOM API (<code>Node</code> オブジェクト、 <code>Document</code>
オブジェクト、その他) は、この版のこの仕様書では労働者に利用可能ではありません。</span></p>


  <h3 id=importing-scripts-and-libraries class="has-ja-translation" data-ja-hash="e7522d998689dc52be80feeff81470ca"><span class=en-original lang=en><span class=secno>5.1 </span>Importing scripts and libraries</span><span class=ja-translation lang=ja><span class=secno>5.1 </span>スクリプトとライブラリーの輸入</span></h3>

  <p class="no-ja-translation" data-ja-hash="66975403bb279c95f3527e7070d78341"><span class=en-original lang=en>When a script invokes the <dfn id=dom-workerglobalscope-importscripts title=dom-WorkerGlobalScope-importScripts><code>importScripts(<var title="">urls</var>)</code></dfn> method on a
  <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object, the user agent must run the
  following steps:</span></p>

  <ol><li><p class="has-ja-translation" data-ja-hash="143a8bb07f4501807d2bbf2d2d2b345a"><span class=en-original lang=en>If there are no arguments, return without doing
   anything. Abort these steps.</span><span class=ja-translation lang=ja>引数がない場合、何も返さずに返ります。
これらの段階を停止します。</span></li>

   <li><p class="has-ja-translation" data-ja-hash="b89818b453add85fbb5ec1e963e3072c"><span class=en-original lang=en><span title="resolve a url">Resolve</span> each
   argument.</span><span class=ja-translation lang=ja>各引数を<span title="resolve a url">解決</span>します。</span></li>

   <li><p class="has-ja-translation" data-ja-hash="54adea3a3a07dd8833ad87eb937142f1"><span class=en-original lang=en>If any fail, throw a <code>SYNTAX_ERR</code>
   exception.</span><span class=ja-translation lang=ja>いずれかが失敗した場合、 <code>SYNTAX_ERR</code> 例外を投げます。</span></li>

<!--
   <li><p class="has-ja-translation" data-ja-hash="952d7bd44378695378ddf1084a1c5347"><span class=en-original lang=en>If any of the resulting <span title="absolute URL">absolute
   URLs</span> have an <span>origin</span> that is not the <span
   title="same origin">same</span> as the origin of the script that
   invoked the method, then throw a <span>security
   exception</span>.</span><span class=ja-translation lang=ja>結果として得られた<span title="absolute URL">絶対
     URL</span>
のいずれかが、メソッドを呼び出したスクリプトの<span>origin</span>と<span
     title="same origin">同じ</span>ではない起源を持つ場合、
<span>保安性例外</span>を投げます。</span></p></li>
-->

   <li>

    <p class="has-ja-translation" data-ja-hash="9a0a1930525c4231da8248d6b7847c8d"><span class=en-original lang=en>Attempt to <span>fetch</span> each resource identified by the
    resulting <span title="absolute URLs">absolute URL</span>.</span><span class=ja-translation lang=ja>結果として得られた<span title="absolute URLs">絶対 URL</span>
によって識別される資源をそれぞれ<span>取得</span>しようと試みます。</span></p>

   </li>

   <li>

    <p class="has-ja-translation" data-ja-hash="4fc5f1898eb20e4c8da603b91c1ae884"><span class=en-original lang=en>For each argument in turn, in the order given, starting with
    the first one, run these substeps:</span><span class=ja-translation lang=ja>各引数について、与えられた順に最初のものから、次の部分段階群を走らせます。</span></p>

    <ol><li>

      <p class="has-ja-translation" data-ja-hash="a5cd8fb5d75985afdc62f7ac228329d4"><span class=en-original lang=en>Wait for the fetching attempt for the corresponding resource
      to complete.</span><span class=ja-translation lang=ja>対応する資源を取得しようとする試みが完了するのを待ちます。</span></p>

      <p class="no-ja-translation" data-ja-hash="c821b5a32a4316df06e95e2117d4d21a"><span class=en-original lang=en>If the fetching attempt failed, throw a
      <code>NETWORK_ERR</code> exception and abort all these
      steps.</span></p>

      <p class="no-ja-translation" data-ja-hash="a2c139226de4390d75b561512be824a7"><span class=en-original lang=en>If the attempt succeeds, then <a href=#decode-a-script-resource title="decode a script
      resource">decode the script resource</a> to obtain its <var title="">source</var>.</span></p>

      <p class="no-ja-translation" data-ja-hash="c880bce97c5a1aadccd8989fc4ec8551"><span class=en-original lang=en>Let <var title="">language</var> be JavaScript.</span></p>

      <p class="note has-ja-translation" data-ja-hash="9d495d7b0fa2439cfa3470c4af977171"><span class=en-original lang=en>As with the worker's script, the script here is
      always assumed to be JavaScript, regardless of the MIME
      type.</span><span class=ja-translation lang=ja>労働者のスクリプトと同じく、ここでのスクリプトも、 MIME 型に関わらず常に
JavaScript であるとみなします。</span></p> <!-- XXX -->

     </li>

     <li>

      <p class="no-ja-translation" data-ja-hash="82bb5f7207d0f40963418cf33df6325b"><span class=en-original lang=en><span>Create a script</span>, using <var title="">source</var> as the script source and <var title="">language</var> as the scripting language, using the
      same global object, browsing context, character encoding, base
      URL, and script group as the <span title=concept-script>script</span> that was created by the
      worker's <a href=#run-a-worker>run a worker</a> algorithm.</span></p>

      <p class="no-ja-translation" data-ja-hash="160451bccc2829032bdfb4597231e9c2"><span class=en-original lang=en>Let the newly created <span title=concept-script>script</span> run until it either
      returns, fails to parse, fails to catch an exception, or gets
      prematurely aborted by the "<a href=#kill-a-worker>kill a worker</a>" or
      "<a href=#terminate-a-worker>terminate a worker</a>" algorithms defined above.</span></p>

      <p class="no-ja-translation" data-ja-hash="41014f4a697396a3e02475a4d61a7472"><span class=en-original lang=en>If it failed to parse, then throw a
      <code>SyntaxError</code><!-- XXX ref? --> exception and abort
      all these steps.</span></p>

      <p class="no-ja-translation" data-ja-hash="32f753089621a99745d3a6dde7c5aa8b"><span class=en-original lang=en>If an exception was raised or if the script was prematurely
      aborted, then abort all these steps, letting the exception or
      aborting continue to be processed by the script that called the
      <code title=dom-WorkerGlobalScope-importScripts><a href=#dom-workerglobalscope-importscripts>importScripts()</a></code>
      method.</span></p>

      <p class="no-ja-translation" data-ja-hash="f41de43eedf5733455078779b5f50c14"><span class=en-original lang=en>If the "<a href=#kill-a-worker>kill a worker</a>" or "<a href=#terminate-a-worker>terminate a
      worker</a>" algorithms abort the script then abort all these
      steps.</span></p>

     </li>

    </ol></li>

  </ol><h3 id=the-navigator-object class="no-ja-translation" data-ja-hash="6a11027ebc14ad36700f251d60a84912"><span class=en-original lang=en><span class=secno>5.2 </span>The <code title=worker-Navigator><a href=#worker-navigator>Navigator</a></code> object</span></h3>

  <p class="no-ja-translation" data-ja-hash="b0a33e2b5cacd5c4c5725f370211c7f4"><span class=en-original lang=en>The <dfn id=dom-worker-navigator title=dom-worker-navigator><code>navigator</code></dfn> attribute
  of the <code><a href=#workerutils>WorkerUtils</a></code> interface must return an instance of
  the <code title=worker-Navigator><a href=#worker-navigator>Navigator</a></code> interface, which
  represents the identity and state of the user agent (the
  client):</span></p>

  <pre class="idl no-ja-translation" data-ja-hash="6d834a5d9279a0ac570d99b54c771186"><span class=en-original lang=en>interface <dfn id=worker-navigator title=worker-Navigator>Navigator</dfn> {};
<a href=#worker-navigator title=worker-Navigator>Navigator</a> implements <span>NavigatorID</span>;
<a href=#worker-navigator title=worker-Navigator>Navigator</a> implements <span>NavigatorOnLine</span>;</span></pre>

  <p class="no-ja-translation" data-ja-hash="f83ff867184de4dcece4621dc2c07096"><span class=en-original lang=en>Objects implementing the <code title=worker-Navigator><a href=#worker-navigator>Navigator</a></code> interface also implement
  the <code>NavigatorID</code> and <code>NavigatorOnLine</code>
  interfaces. <a href=#refsHTML5>[HTML5]</a></span></p>

  <p class="note no-ja-translation" data-ja-hash="67986732437eb5b67c3e1bd21f1325a8"><span class=en-original lang=en>The <code title=worker-Navigator><a href=#worker-navigator>Navigator</a></code>
  interface defined in this specification is different than the one
  defined in the HTML specification.</span></p>


  <h3 id=apis-defined-in-other-specifications class="has-ja-translation" data-ja-hash="d6d6885373ce92bfa8857f5a375a9c8f"><span class=en-original lang=en><span class=secno>5.3 </span>APIs defined in other specifications</span><span class=ja-translation lang=ja><span class=secno>5.3 </span>他の仕様書で定義されている API</span></h3>

  <p class="no-ja-translation" data-ja-hash="1280f8909e789b1739534938ee2d8974"><span class=en-original lang=en>The <code title=dom-opendatabase>openDatabase()</code> and
  <code title=dom-opendatabase-sync>openDatabaseSync()</code>
  methods are defined in the Web Database specification. <a href=#refsWEBDATABASE>[WEBDATABASE]</a></span></p>


  <h3 id=interface-objects-and-constructors class="has-ja-translation" data-ja-hash="78e75b89c304218ef77a66cd9efdf398"><span class=en-original lang=en><span class=secno>5.4 </span>Interface objects and constructors</span><span class=ja-translation lang=ja><span class=secno>5.4 </span>界面オブジェクトと構築器</span></h3>

  <p class="no-ja-translation" data-ja-hash="891d0a43200fedd7ae183f012070bb93"><span class=en-original lang=en>There must be no interface objects and constructors available in
  the global scope of scripts whose <span>script execution
  context</span> is a <code><a href=#workerglobalscope>WorkerGlobalScope</a></code> object except for
  the following:</span></p>

  <ul><li><p class="no-ja-translation" data-ja-hash="a8f4727ef88dc7955f089bfa420d3c65"><span class=en-original lang=en><code>XMLHttpRequest</code> and all interface objects and
   constructors defined by the XMLHttpRequest specifications, except
   that the <span>document response entity body</span> must always be
   null. The <span><code>XMLHttpRequest</code> base URL</span> is the
   <span>script's base URL</span>; the
   <span><code>XMLHttpRequest</code> origin</span> is the script's
   <span>origin</span>. <a href=#refsXHR>[XHR]</a></span></li>

   <li><p class="no-ja-translation" data-ja-hash="dd3bea5f0bf238db87ad9fb59c7be62a"><span class=en-original lang=en>The <code>WebSocket</code> interface object and
   constructor. <a href=#refsWEBSOCKET>[WEBSOCKET]</a></span></li>

   <li><p class="no-ja-translation" data-ja-hash="bbeb4f3911ac8aedf89935a07d70106c"><span class=en-original lang=en>The <code>EventSource</code> interface object and
   constructor. <a href=#refsEVENTSOURCE>[EVENTSOURCE]</a></span></li>

   <li><p class="no-ja-translation" data-ja-hash="939ce12ed8f8d8ce1888e6c380db792c"><span class=en-original lang=en>The <code>MessageChannel</code> interface object and
   constructor. <a href=#refsHTML5>[HTML5]</a></span></li>

   <li><p class="no-ja-translation" data-ja-hash="0ca0874e3173f58421ed4537975fdd7f"><span class=en-original lang=en>The <code title=dom-Worker><a href=#dom-worker>Worker()</a></code> and <code title=dom-SharedWorker><a href=#dom-sharedworker>SharedWorker(<var title="">url</var>)</a></code> constructors.</span></li>

  </ul><h3 id=worker-locations class="has-ja-translation" data-ja-hash="ae4aa0f882fcbd2ee8252e59113ec205"><span class=en-original lang=en><span class=secno>5.5 </span>Worker locations</span><span class=ja-translation lang=ja><span class=secno>5.5 </span>労働者の所在</span></h3>

  <pre class="idl no-ja-translation" data-ja-hash="8d12e26ffacf32cd9d10364c0255ab53"><span class=en-original lang=en>interface <dfn id=workerlocation>WorkerLocation</dfn> {
  readonly attribute DOMString <a href=#dom-workerlocation-href title=dom-WorkerLocation-href>href</a>;
  readonly attribute DOMString <a href=#dom-workerlocation-protocol title=dom-WorkerLocation-protocol>protocol</a>;
  readonly attribute DOMString <a href=#dom-workerlocation-host title=dom-WorkerLocation-host>host</a>;
  readonly attribute DOMString <a href=#dom-workerlocation-hostname title=dom-WorkerLocation-hostname>hostname</a>;
  readonly attribute DOMString <a href=#dom-workerlocation-port title=dom-WorkerLocation-port>port</a>;
  readonly attribute DOMString <a href=#dom-workerlocation-pathname title=dom-WorkerLocation-pathname>pathname</a>;
  readonly attribute DOMString <a href=#dom-workerlocation-search title=dom-WorkerLocation-search>search</a>;
  readonly attribute DOMString <a href=#dom-workerlocation-hash title=dom-WorkerLocation-hash>hash</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="0875217b900933e0434228878aa70bb1"><span class=en-original lang=en>A <code><a href=#workerlocation>WorkerLocation</a></code> object represents an <span>absolute
  URL</span> set at its creation.</span></p>

  <p class="no-ja-translation" data-ja-hash="12d68ceea5131e0a3f4acc5b2060ee25"><span class=en-original lang=en>The <dfn id=dom-workerlocation-href title=dom-WorkerLocation-href><code>href</code></dfn>
  attribute must return the <span>absolute URL</span> that the object
  represents.</span></p>

  <p class="no-ja-translation" data-ja-hash="911e900b0ce6080a962f5d5c782239d4"><span class=en-original lang=en>The <code><a href=#workerlocation>WorkerLocation</a></code> interface also has the complement
  of <span>URL decomposition IDL attributes</span>, <dfn id=dom-workerlocation-protocol title=dom-WorkerLocation-protocol><code>protocol</code></dfn>,
  <dfn id=dom-workerlocation-host title=dom-WorkerLocation-host><code>host</code></dfn>, <dfn id=dom-workerlocation-port title=dom-WorkerLocation-port><code>port</code></dfn>, <dfn id=dom-workerlocation-hostname title=dom-WorkerLocation-hostname><code>hostname</code></dfn>,
  <dfn id=dom-workerlocation-pathname title=dom-WorkerLocation-pathname><code>pathname</code></dfn>,
  <dfn id=dom-workerlocation-search title=dom-WorkerLocation-search><code>search</code></dfn>,
  and <dfn id=dom-workerlocation-hash title=dom-WorkerLocation-hash><code>hash</code></dfn>. These must
  follow the rules given for URL decomposition IDL attributes, with the
  <span title=concept-uda-input>input</span> being the
  <span>absolute URL</span> that the object represents (same as the
  <code title=dom-WorkerLocation-href><a href=#dom-workerlocation-href>href</a></code> attribute), and
  the <span title=concept-uda-setter>common setter action</span>
  being a no-op, since the attributes are defined to be readonly. <a href=#refsHTML5>[HTML5]</a></span></p>


  <h2 class="no-num has-ja-translation" data-ja-hash="d95867deadfe690e40f42068d6b59df8" id=references><span class=en-original lang=en>References</span><span class=ja-translation lang=ja>参照</span></h2><!--REFS-->

  <p class="no-ja-translation" data-ja-hash="753b3f31f2391081a7d0512d99c97790"><span class=en-original lang=en>All references are normative unless marked "Non-normative".</span></p>

  <dl><dt id=refsDOMCORE class="no-ja-translation" data-ja-hash="bc16cdf6ab9118cf4065dd05b4725405"><span class=en-original lang=en>[DOMCORE]</span></dt>
   <dd class="no-ja-translation" data-ja-hash="7fc13e52bc2a6201412c03a4c373ccf3"><span class=en-original lang=en><cite><a href=http://www.w3.org/TR/DOM-Level-3-Core/>Document
   Object Model (DOM) Level 3 Core Specification</a></cite>, A. Le
   Hors, P. Le Hegaret, L. Wood, G. Nicol, J. Robie, M. Champion,
   S. Byrnes. W3C, April 2004.</span></dd>
   <!--
   <dd class="no-ja-translation" data-ja-hash="e06e3d48fc44cb5377f215903eac8c64"><span class=en-original lang=en><cite><a href="http://simon.html5.org/specs/web-dom-core">Web
   DOM Core</a></cite>, S. Pieters. W3C, June 2009.</span></dd>
   -->

   <dt id=refsDOMEVENTS class="no-ja-translation" data-ja-hash="4acfe87f4af565e925ab2c05d359f9b1"><span class=en-original lang=en>[DOMEVENTS]</span></dt>
   <!--
   <dd class="no-ja-translation" data-ja-hash="fa7c84f91358fa9f83f95423f9d0c22a"><span class=en-original lang=en><cite><a
   href="http://www.w3.org/TR/DOM-Level-3-Events/">Document Object
   Model (DOM) Level 3 Events Specification</a></cite>,
   B. H&ouml;hrmann, P. Le Hegaret, T. Pixley. W3C, December
   2007.</span></dd>
   -->
   <dd class="no-ja-translation" data-ja-hash="be06d912f9b000a6d47674b7ff3b65d5"><span class=en-original lang=en><cite><a href=http://dev.w3.org/2006/webapi/DOM-Level-3-Events/html/DOM3-Events.html>Document
   Object Model (DOM) Level 3 Events Specification</a></cite>,
   D. Schepers. W3C, July 2009.</span></dd>

   <dt id=refsECMA262 class="no-ja-translation" data-ja-hash="ef033ad77bafa67936e26b8da6095aed"><span class=en-original lang=en>[ECMA262]</span></dt>
   <dd class="no-ja-translation" data-ja-hash="98a50a41a8dd161cc16a826da0377562"><span class=en-original lang=en><cite><a href=http://www.ecma-international.org/publications/standards/Ecma-262.htm>ECMAScript
   Language Specification</a></cite>. ECMA, December 1999.</span></dd>

   <dt id=refsEVENTSOURCE class="no-ja-translation" data-ja-hash="e7e8ca9d7ad98af783c5437257c5ebc5"><span class=en-original lang=en>[EVENTSOURCE]</span></dt>
   <!--
   <dd class="no-ja-translation" data-ja-hash="bb55f3919043f35a4adca2f15ec20278"><span class=en-original lang=en><cite><a href="http://www.w3.org/TR/eventsource/">Server-Sent
   Events</a></cite>, I. Hickson. W3C, April 2009.</span></dd>
   -->
   <dd class="no-ja-translation" data-ja-hash="b9db8e13e3a07aa962a840d0f53d10ac"><span class=en-original lang=en><cite><a href=http://dev.w3.org/html5/eventsource/>Server-Sent
   Events</a></cite>, I. Hickson. W3C, July 2009.</span></dd>

   <dt id=refsHTML5 class="no-ja-translation" data-ja-hash="c8334fcd95059386411d0d14d5bdbeab"><span class=en-original lang=en>[HTML5]</span></dt>
   <!--
   <dd class="no-ja-translation" data-ja-hash="de23a7ad9840c8df08cbc8237472b341"><span class=en-original lang=en><cite><a href="http://www.w3.org/TR/html5/">HTML5</a></cite>,
   I. Hickson, D. Hyatt. W3C, April 2009.</span></dd>
   <dd class="no-ja-translation" data-ja-hash="a313fc8fc4a8517dbed899bae6562d24"><span class=en-original lang=en><cite><a
   href="http://www.w3.org/html/wg/html5/">HTML5</a></cite>,
   I. Hickson, D. Hyatt. W3C, August 2009.</span></dd>
   -->
   <dd class="no-ja-translation" data-ja-hash="6e52796fd453c105fc2d2a18e6ce549a"><span class=en-original lang=en><cite><a href=http://www.whatwg.org/specs/web-apps/current-work/>HTML5</a></cite>,
   I. Hickson. WHATWG, August 2009.</span></dd>

   <dt id=refsRFC2119 class="no-ja-translation" data-ja-hash="160a6b695c5227ccd5c7beb0e6d5ec22"><span class=en-original lang=en>[RFC2119]</span></dt>
   <dd class="no-ja-translation" data-ja-hash="6ae46a2eda05406ae93aa57e2c1d3ac4"><span class=en-original lang=en><cite><a href=http://www.ietf.org/rfc/rfc2119.txt>Key words for use in
   RFCs to Indicate Requirement Levels</a></cite>, S. Bradner. IETF, March
   1997.</span></dd>

   <dt id=refsWEBDATABASE class="no-ja-translation" data-ja-hash="f94817bc9b7ef609fd84e9f95c627302"><span class=en-original lang=en>[WEBDATABASE]</span></dt>
   <dd class="no-ja-translation" data-ja-hash="cc7b64af714b7157dc4f9d82981c71b3"><span class=en-original lang=en><cite><a href=http://dev.w3.org/html5/webdatabase/>Web
   Database</a></cite>, I. Hickson. W3C, July
   2009.</span></dd>

   <dt id=refsWEBIDL class="no-ja-translation" data-ja-hash="c36d8342bfa57c496487e73bea1fb4d2"><span class=en-original lang=en>[WEBIDL]</span></dt>
   <!--
   <dd class="no-ja-translation" data-ja-hash="abfc3d3081264da39586fa27500c0735"><span class=en-original lang=en><cite><a href="http://www.w3.org/TR/WebIDL/">Web
   IDL</a></cite>, C. McCormack. W3C, December 2008.</span></dd>
   -->
   <dd class="no-ja-translation" data-ja-hash="c6e22f55f1fdbf826fd96ab00d2e89ce"><span class=en-original lang=en><cite><a href=http://dev.w3.org/2006/webapi/WebIDL/>Web
   IDL</a></cite>, C. McCormack. W3C, July 2009.</span></dd>

   <dt id=refsWEBSOCKET class="no-ja-translation" data-ja-hash="15823683133ea3fcc5ab28cf16493c4d"><span class=en-original lang=en>[WEBSOCKET]</span></dt>
   <!--
   <dd class="no-ja-translation" data-ja-hash="0cc50f9b1853d25971b2be26d4f0751f"><span class=en-original lang=en><cite><a href="http://www.w3.org/TR/websockets/">The Web Sockets
   API</a></cite>, I. Hickson. W3C, April
   2009.</span></dd>
   -->
   <dd class="no-ja-translation" data-ja-hash="fff159651795cafc5a95a29ad79ef67c"><span class=en-original lang=en><cite><a href=http://dev.w3.org/html5/websockets/>The Web Sockets
   API</a></cite>, I. Hickson. W3C, August
   2009.</span></dd>

   <dt id=refsXHR class="no-ja-translation" data-ja-hash="3ba5cbb19a05fab102ccbee69603b1fc"><span class=en-original lang=en>[XHR]</span></dt>
   <!--
   <dd class="no-ja-translation" data-ja-hash="33fc4916633611a40e016c3e784b1522"><span class=en-original lang=en><cite><a href="http://www.w3.org/TR/XMLHttpRequest/">The XMLHttpRequest
   Object</a></cite>, A. van Kesteren. W3C, April
   2008.</span></dd>
   -->
   <dd class="no-ja-translation" data-ja-hash="e5be364ffb4ddc867033669399b0ee1d"><span class=en-original lang=en><cite><a href=http://dev.w3.org/2006/webapi/XMLHttpRequest-2/><code>XMLHttpRequest</code></a></cite>,
   A. van Kesteren. W3C, June 2009.</span></dd>

  </dl><h2 class="no-num has-ja-translation" data-ja-hash="0407c27180c9b019e644e8ad4c6a9324" id=acknowledgements><span class=en-original lang=en>Acknowledgements</span><span class=ja-translation lang=ja>謝辞</span></h2> <!-- ACKS -->

  <p class="has-ja-translation" data-ja-hash="a17a0feb6f58a31040d51121e80bc233" data-ja-real-hash="f59286e011a68a30c6514aae2845f151"><span class=en-original lang=en>Thanks to

  Aaron Boodman,
  &#1040;&#1083;&#1077;&#1082;&#1089;&#1077;&#1081; &#1055;&#1088;&#1086;&#1089;&#1082;&#1091;&#1088;&#1103;&#1082;&#1086;&#1074; (Alexey Proskuryakov),
  Anne van Kesteren,
  Ben Turner,
  Dmitry Titov,
  Drew Wilson,
  Jeremy Orlow,
  Jonas Sicking,
  Justin James,
  Kevin Hakanson,
  Maciej Stachowiak,
  Michael Nordman,
  Mike Smith,

  and

  Philip Taylor

  for their useful and substantial comments.</span><span class=ja-translation lang=ja>Aaron Boodman, &#1040;&#1083;&#1077;&#1082;&#1089;&#1077;&#1081; &#1055;&#1088;&#1086;&#1089;&#1082;&#1091;&#1088;&#1103;&#1082;&#1086;&#1074; (Alexey Proskuryakov), Anne van Kesteren, Ben Turner, Dmitry Titov, Drew Wilson, Jeremy Orlow, Jonas Sicking, Justin James, Kevin Hakanson, Maciej Stachowiak, Michael Nordman, Mike Smith, Philip Taylor の有用かつ重要なコメントに感謝します。</span></p>

  <p class="has-ja-translation" data-ja-hash="7c6875278ecf56df193c33c553856fac"><span class=en-original lang=en>Huge thanks to the whole Gears team, who pioneered this
  technology and whose experience has been a huge influence on this
  specification.</span><span class=ja-translation lang=ja>Gears チームの方々にも非常に感謝します。
Gears チームの方々はこの技術を開拓し、その経験はこの仕様書にも多大な影響を与えています。
</span></p>

 