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


<html lang=en-US-x-hixie>
 <head>
  <title>Web Workers</title>
  <link href=http://www.whatwg.org/style/specification rel=stylesheet>
<link href=ja-style rel=stylesheet>
<link href=only-ja-style rel="stylesheet" title="Show only Japanese text" id=style-only-ja>
<link href=both-en-ja-style rel="alternate stylesheet" title="Show both English and Japanese texts" id=style-both-en-ja>
<script src=ja-script defer async></script>
  <link href="/images/icon" rel=icon>

  <style>
   p > span:not([title=""]):not([class="big-issue"]), li > span:not([title=""]):not([class="big-issue"]) { border-bottom: solid #99CC99; }
  </style>

 <body class=draft>
  <div class=head>
   <p class="no-ja-translation" data-ja-hash="b20329e0f615f58f17900e708fa8dbaf"><span class=en-original lang=en><a class=logo href="http://www.whatwg.org/" rel=home><img alt=WHATWG
    src="/images/logo"></a></span></p>

   <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="9ea0914ebe364045b80e1ff1a8a2ec1e" data-ja-real-hash="f9ac838f2da2411141e832aaef934f67" id=draft><span class=en-original lang=en>Draft Recommendation &mdash; 14 January
    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1月14日</span></h2>

   <p class="no-ja-translation" data-ja-hash="54759c46800b2712dd15f6097ee6ed63"><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></p>

   <p class="has-ja-translation" data-ja-hash="6a0ea97471522df19cf042a8869d7c52"><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。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. 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><button type=button onclick="
  document.getElementById ('style-only-ja').disabled = false;
  document.getElementById ('style-both-en-ja').disabled = true;
">日本語訳だけ表示 <span lang=en>Show only Japanese translation</span></button>
<p><button type=button onclick="
  document.getElementById ('style-only-ja').disabled = true;
  document.getElementById ('style-both-en-ja').disabled = false;
">英和対訳表示 <span lang=en>Show both English and Japanese texts</span></button>

<p class=XXX>原文が更新されて新しい仕様書生成スクリプトを使うようになるまで、
この仕様書の訳文の追加・改訂はお控えください。
</ins>

<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><dd class="no-ja-translation" data-ja-hash="a713841c83aed89ce71b7ee6b51cb2cb"><span class=en-original lang=en><a
     href="http://www.whatwg.org/specs/web-workers/current-work/">http://whatwg.org/ww</a>

    </span><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><dd class="no-ja-translation" data-ja-hash="609cec19ff8d697eb0a9f7a0104e0bfb"><span class=en-original lang=en>Twitter messages (non-editorial changes only): <a
     href="http://twitter.com/WHATWG">http://twitter.com/WHATWG</a>

    </span><dd class="no-ja-translation" data-ja-hash="abaab2a9b4d1bd0f43a2293e5d1fff4d"><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><dd class="has-ja-translation" data-ja-hash="5e1dbca74cface6f0d0ea523340e6a89" data-ja-real-hash="f82128f124c19a67cc2104420cc99c45"><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 class="has-ja-translation" data-ja-hash="ea5cbdd06bfb529e4a1bcfeac9cfbd61" data-ja-real-hash="ae455a827d3d1e5b15fd14df54502cf5"><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><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><dd class="no-ja-translation" data-ja-hash="72b4306377796146b832d635c9b791f4"><span class=en-original lang=en>To send feedback: <a
     href="http://www.whatwg.org/mailing-list">[email protected]</a>

    </span><dd class="no-ja-translation" data-ja-hash="7e3aaf1187bd798f9f71dd7e6e4fa9fe"><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><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><dd class="no-ja-translation" data-ja-hash="220fb2ab7924ad62bc8567b8b9c5f0f8"><span class=en-original lang=en>Ian Hickson, Google, [email protected]
   </span></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><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="no-ja-translation" data-ja-hash="3f706d8337b443d9a959c36a9b3677a3"><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><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 class="no-ja-translation" data-ja-hash="75e78507b984cae37464af998b8dc8a2"><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><p class="no-ja-translation" data-ja-hash="bb77e82ccfbb3bd01ee25d2bf7243a07"><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><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-->

  <ul class=toc>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="ab1b3562495830cab4f7e657b0f8c3de"><span class=en-original lang=en><a href="#introduction"><span class=secno>1 </span>Introduction</a>
    </span><ul class=toc>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="f94143aeed3bb9197ca798364046d48d"><span class=en-original lang=en><a href="#scope"><span class=secno>1.1 </span>Scope</a>

     </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="cc8223ec55502c55628f56c7b446f30d"><span class=en-original lang=en><a href="#tutorial"><span class=secno>1.2 </span>Tutorial</a>
      </span><ul class=toc>
       <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="0b86907a8660d3b6a1f8c570573c5d91"><span class=en-original lang=en><a href="#a-background"><span class=secno>1.2.1 </span>A
        background number-crunching worker</a>

       </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="b61c5d843d6ba7a4c8c70016e0204883"><span class=en-original lang=en><a href="#a-worker"><span class=secno>1.2.2 </span>A worker for
        updating a client-side database</a>

       </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="357d53d20d468842935342e9432d1d78"><span class=en-original lang=en><a href="#worker"><span class=secno>1.2.3 </span>Worker used for
        background I/O</a>

       </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="abbe71ab70eaeb3035910c4b5987d1d5"><span class=en-original lang=en><a href="#shared"><span class=secno>1.2.4 </span>Shared
        workers</a>

       </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="ad63a3c0da0bfe49cb5391ca4539ddbc"><span class=en-original lang=en><a href="#delegation"><span class=secno>1.2.5
        </span>Delegation</a>

       </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="76e6c63eebe871d10886f8bac07ffa91"><span class=en-original lang=en><a href="#providing"><span class=secno>1.2.6 </span>Providing
        libraries</a>
      </span></ul>

     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="f1dee0568312d45ee4fb42e24fbb33d7"><span class=en-original lang=en><a href="#conformance"><span class=secno>1.3 </span>Conformance
      requirements</a>
      </span><ul class=toc>
       <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="9cf46931a24bdd95446cc0dc13d70962"><span class=en-original lang=en><a href="#dependencies"><span class=secno>1.3.1
        </span>Dependencies</a>
      </span></ul>

     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="f14a8054db0709988c39b4986c4a8754"><span class=en-original lang=en><a href="#terminology"><span class=secno>1.4 </span>Terminology</a>
    </span></ul>

   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="1e8592ba7cd5e7e8258733b6ac72589e"><span class=en-original lang=en><a href="#infrastructure"><span class=secno>2
    </span>Infrastructure</a>
    </span><ul class=toc>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="5763bf8b68038d9e7b7d492bd3ae7bab"><span class=en-original lang=en><a href="#the-global"><span class=secno>2.1 </span>The global
      scope</a>
      </span><ul class=toc>
       <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="efb0edfb19efd26410cb99ab1525f948"><span class=en-original lang=en><a href="#the-workerglobalscope"><span class=secno>2.1.1
        </span>The <code>WorkerGlobalScope</code> abstract interface</a>

       </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="5f99bbc9217feadbd07b63a59fb5f291"><span class=en-original lang=en><a href="#dedicated"><span class=secno>2.1.2 </span>Dedicated
        workers and the <code>DedicatedWorkerGlobalScope</code> interface</a>
        

       </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="ba3044d55b8091a7410ee51a58225f09"><span class=en-original lang=en><a href="#shared0"><span class=secno>2.1.3 </span>Shared workers
        and the <code>SharedWorkerGlobalScope</code> inteface</a>
      </span></ul>

     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="c2a16736e5155efbee09ceec52062868"><span class=en-original lang=en><a href="#base-urls"><span class=secno>2.2 </span>Base URLs and
      origins of workers</a>

     </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="22ee8106fe8009d8a712074798cd2f31"><span class=en-original lang=en><a href="#the-event"><span class=secno>2.3 </span>The event loop</a>
      

     </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="9c88712c50f8e878f1e2900817520600"><span class=en-original lang=en><a href="#the-workers"><span class=secno>2.4 </span>The worker's
      ports</a>

     </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="a6149718eb643990db06957bc18edefd"><span class=en-original lang=en><a href="#processing"><span class=secno>2.5 </span>Processing
      model</a>
      </span><ul class=toc>
       <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="986de6477b945859c87547990aad9a6c"><span class=en-original lang=en><a href="#runtime"><span class=secno>2.5.1 </span>Runtime script
        errors</a>
      </span></ul>

     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="fdab759854cb648250afe4a81693b117"><span class=en-original lang=en><a href="#creating"><span class=secno>2.6 </span>Creating
      workers</a>
      </span><ul class=toc>
       <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="77dfb5f9a16bd5b77a73bdd3617c760e"><span class=en-original lang=en><a href="#the-abstractworker"><span class=secno>2.6.1 </span>The
        <code>AbstractWorker</code> abstract interface</a>

       </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="bbddb6f68afde611f94369aa5a0ad020"><span class=en-original lang=en><a href="#dedicated0"><span class=secno>2.6.2 </span>Dedicated
        workers and the <code>Worker</code> interface</a>

       </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="1f5bc4a5d6e1eb7e6293adfe42e9818c"><span class=en-original lang=en><a href="#shared1"><span class=secno>2.6.3 </span>Shared workers
        and the <code>SharedWorker</code> interface</a>
      </span></ul>
    </ul>

   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="d86645fe6c38077b82c758dab4b2d506"><span class=en-original lang=en><a href="#apis-available"><span class=secno>3 </span>APIs available to
    workers</a>
    </span><ul class=toc>
     <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="72f3123f6e8b15f48de8a349c9982513"><span class=en-original lang=en><a href="#importing"><span class=secno>3.1 </span>Importing scripts
      and libraries</a>

     </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="05a994c34b6bbbd32ecf8b83d319c68d"><span class=en-original lang=en><a href="#the-navigator"><span class=secno>3.2 </span>The
      <code>Navigator</code> object</a>

     </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="23c1fe849cb20e56a903c0fc2b325b0c"><span class=en-original lang=en><a href="#apis-defined"><span class=secno>3.3 </span>APIs defined in
      other specifications</a>

     </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="ebb66d4419ae73eae722f90404b3c573"><span class=en-original lang=en><a href="#interface"><span class=secno>3.4 </span>Interface objects
      and constructors</a>

     </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="951dcfbf081177ae0184ead7e82074f7"><span class=en-original lang=en><a href="#worker0"><span class=secno>3.5 </span>Worker locations</a>
      
    </span></ul>

   <li class=no-num><p class="no-ja-translation ja-translation-inserted" data-ja-hash="e747237bceaf9dabea52363254fc5f16"><span class=en-original lang=en><a href="#references">References</a>

   </span><li class=no-num><p class="no-ja-translation ja-translation-inserted" data-ja-hash="f440038177834afbee04ac5e84ec86fe"><span class=en-original lang=en><a href="#acknowledgements">Acknowledgements</a>
  </span></ul>
  <!--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="has-ja-translation" data-ja-hash="585b83d0801ae75a14554d8d2c737fb2"><span class=en-original lang=en><em>This section is non-normative.</em>

  </span><span class=ja-translation lang=ja><em>この節は規定の一部ではありません。</em></span><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 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 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 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><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="has-ja-translation" data-ja-hash="585b83d0801ae75a14554d8d2c737fb2"><span class=en-original lang=en><em>This section is non-normative.</em>

  </span><span class=ja-translation lang=ja><em>この節は規定の一部ではありません。</em></span><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><h4 id=a-background 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="has-ja-translation" data-ja-hash="585b83d0801ae75a14554d8d2c737fb2"><span class=en-original lang=en><em>This section is non-normative.</em>

  </span><span class=ja-translation lang=ja><em>この節は規定の一部ではありません。</em></span><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 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 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><pre class="no-ja-translation" data-ja-hash="537851d8b0d221cfefc798638131dbcd"><span class=en-original lang=en>&lt;!DOCTYPE HTML>
&lt;html>
 &lt;head>
  &lt;title>Worker example: One-core computation&lt;/title>
 &lt;/head>
 &lt;body>
  &lt;p>The highest prime number discovered so far is: &lt;output id="result">&lt;/output>&lt;/p>
  &lt;script>
   var worker = new Worker('worker.js');
   worker.onmessage = function (event) {
     document.getElementById('result').textContent = event.data;
   };
  &lt;/script>
 &lt;/body>
&lt;/html></span></pre>

  <p class="no-ja-translation" data-ja-hash="e4adb9b72fb3bd211cbc81bffd5d4622"><span class=en-original lang=en>The <code title=dom-Worker><a href="#worker2">Worker()</a></code>
   constructor call creates a worker and returns a <code><a
   href="#worker1">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="#onmessage0">onmessage</a></code>
   event handler attribute allows the code to receive messages from the
   worker.

  </span><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><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="6cbc84e07a533681566aa4fdf838f852"><span class=en-original lang=en>The bulk of this code is simply an unoptimised search for a prime
   number. To send a message back to the page, the <code
   title=dom-DedicatedWorkerGlobalScope-postMessage><a
   href="#postmessage">postMessage()</a></code> method is used to post a
   message when a prime is found.

  </span><p class="has-ja-translation" data-ja-hash="add583522732edb8aca6202c451ddb27" data-ja-real-hash="fb1b85e403d4ca967bb53b221e757de8"><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><h4 id=a-worker 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="has-ja-translation" data-ja-hash="585b83d0801ae75a14554d8d2c737fb2"><span class=en-original lang=en><em>This section is non-normative.</em>

  </span><span class=ja-translation lang=ja><em>この節は規定の一部ではありません。</em></span><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 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><pre class="no-ja-translation" data-ja-hash="1fa3b8ca6e1be5ba6915c7164f359cf2"><span class=en-original lang=en>&lt;script>
 new Worker('worker.js');
&lt;/script></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><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 class="no-ja-translation" data-ja-hash="d47c2ada69bdfebeb58219610105a1d7"><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><h4 id=worker 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="has-ja-translation" data-ja-hash="585b83d0801ae75a14554d8d2c737fb2"><span class=en-original lang=en><em>This section is non-normative.</em>

  </span><span class=ja-translation lang=ja><em>この節は規定の一部ではありません。</em></span><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 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><pre class="no-ja-translation" data-ja-hash="ba58233c15e0292446559987f277f4a6"><span class=en-original lang=en>&lt;!DOCTYPE HTML>
&lt;html>
 &lt;head>
  &lt;title>Worker example: Stock ticker&lt;/title>
  &lt;script>
   // 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>
 &lt;/head>
 &lt;body>
  &lt;p>&lt;output id="symbol">&lt;/output> &lt;output id="value">&lt;/output>&lt;/p>
  &lt;script>
   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>
  &lt;p>&lt;label>Search: &lt;input type="text" oninput="search(this.value)">&lt;/label>&lt;/p>
  &lt;ul id="results">&lt;/ul>
  &lt;script>
   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>
  &lt;p>(The data in this example is not real. Try searching for "Google" or "Apple".)&lt;/p>
 &lt;/body>
&lt;/html></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><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><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><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="9b529b56f810a73a138b067e5dfe89cd"><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><h4 id=shared 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="has-ja-translation" data-ja-hash="585b83d0801ae75a14554d8d2c737fb2"><span class=en-original lang=en><em>This section is non-normative.</em>

  </span><span class=ja-translation lang=ja><em>この節は規定の一部ではありません。</em></span><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 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><pre class="no-ja-translation" data-ja-hash="55a104a8ba6c7596b2ca462c2ffb1f0a"><span class=en-original lang=en>&lt;!DOCTYPE HTML>
&lt;html>
 &lt;head>
  &lt;title>Workers example: Multiviewer&lt;/title>
  &lt;script>
   function openViewer() {
     window.open('viewer.html');
   }
  &lt;/script>
 &lt;/head>
 &lt;body>
  &lt;p>&lt;button type=button onclick="openViewer()">Open a new
  viewer&lt;/button>&lt;/p>
  &lt;p>Each viewer opens in a new window. You can have as many viewers
  as you like, they all view the same data.&lt;/p>
 &lt;/body>
&lt;/html></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><pre class="no-ja-translation" data-ja-hash="99dd203a533b07b5af460448666b5a5e"><span class=en-original lang=en>&lt;!DOCTYPE HTML>
&lt;html>
 &lt;head>
  &lt;title>Workers example: Multiviewer viewer&lt;/title>
  &lt;script>
   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> 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.port;
     // 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>
 &lt;/head>
 &lt;body>
  &lt;h1>Viewer&lt;/h1>
  &lt;h2>Map&lt;/h2>
  &lt;p>&lt;canvas id="map" height=150 width=150>&lt;/canvas>&lt;/p>
  &lt;p>
   &lt;button type=button onclick="worker.port.postMessage('mov left')">Left&lt;/button>
   &lt;button type=button onclick="worker.port.postMessage('mov up')">Up&lt;/button>
   &lt;button type=button onclick="worker.port.postMessage('mov down')">Down&lt;/button>
   &lt;button type=button onclick="worker.port.postMessage('mov right')">Right&lt;/button>
   &lt;button type=button onclick="worker.port.postMessage('set 0')">Set 0&lt;/button>
   &lt;button type=button onclick="worker.port.postMessage('set 1')">Set 1&lt;/button>
  &lt;/p>
  &lt;h2>Public Chat&lt;/h2>
  &lt;dialog id="public">&lt;/dialog>
  &lt;form onsubmit="worker.port.postMessage('txt ' + message.value); message.value = ''; return false;">
   &lt;p>
    &lt;input type="text" name="message" size="50">
    &lt;button>Post&lt;/button>
   &lt;/p>
  &lt;/form>
  &lt;h2>Private Chat&lt;/h2>
  &lt;ul id="private">&lt;/ul>
 &lt;/body>
&lt;/html>
</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 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 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 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><pre class="no-ja-translation" data-ja-hash="70993f8765f69b748af6943ac4387c72"><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 >= 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 >= 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.port._name = getNextName();
  event.port._data = { port: event.port, x: 0, y: 0, };
  viewers[event.port._name] = event.port._data;
  event.port.postMessage('cfg ' + name);
  event.port.onmessage = getMessage;
  sendMapData(event.port.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="b0014972506b918202f48b09f30424bd"><span class=en-original lang=en><strong>Connecting to multiple pages</strong>. The script uses the <code
   title=handler-SharedWorkerGlobalScope-onconnect><a
   href="#onconnect">onconnect</a></code> event listener to listen for
   multiple connections.

  </span><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 class="has-ja-translation" data-ja-hash="add583522732edb8aca6202c451ddb27" data-ja-real-hash="4c5ed82f8da671a56292686cc3a60981"><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><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="has-ja-translation" data-ja-hash="585b83d0801ae75a14554d8d2c737fb2"><span class=en-original lang=en><em>This section is non-normative.</em>

  </span><span class=ja-translation lang=ja><em>この節は規定の一部ではありません。</em></span><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 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><pre class="no-ja-translation" data-ja-hash="537851d8b0d221cfefc798638131dbcd"><span class=en-original lang=en>&lt;!DOCTYPE HTML>
&lt;html>
 &lt;head>
  &lt;title>Worker example: One-core computation&lt;/title>
 &lt;/head>
 &lt;body>
  &lt;p>The highest prime number discovered so far is: &lt;output id="result">&lt;/output>&lt;/p>
  &lt;script>
   var worker = new Worker('worker.js');
   worker.onmessage = function (event) {
     document.getElementById('result').textContent = event.data;
   };
  &lt;/script>
 &lt;/body>
&lt;/html></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><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 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><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 class="has-ja-translation" data-ja-hash="add583522732edb8aca6202c451ddb27" data-ja-real-hash="c560664d07d84902d5e9e6c68ffc2f01"><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><h4 id=providing 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="has-ja-translation" data-ja-hash="585b83d0801ae75a14554d8d2c737fb2"><span class=en-original lang=en><em>This section is non-normative.</em>

  </span><span class=ja-translation lang=ja><em>この節は規定の一部ではありません。</em></span><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><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><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><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><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><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><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></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><pre class="no-ja-translation" data-ja-hash="ece93540f76bf50f9d9ac650f14a714c"><span class=en-original lang=en>function handleMessage(e) {
  if (e.data == "genkeys")
    genkeys(e.port);
  else if (e.data == "encrypt")
    encrypt(e.port);
  else if (e.data == "decrypt")
    decrypt(e.port);
}

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 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><pre class="no-ja-translation" data-ja-hash="02df9ec9921dac18bca9782664a47c5b"><span class=en-original lang=en>&lt;!DOCTYPE HTML>
&lt;html>
 &lt;head>
  &lt;title>Worker example: Crypto library&lt;/title>
  &lt;script>
   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>
  &lt;style>
   textarea { display: block; }
  &lt;/style>
 &lt;/head>
 &lt;body onload="getKeys()">
  &lt;fieldset>
   &lt;legend>Keys&lt;/legend>
   &lt;p>&lt;label>Public Key: &lt;textarea id="public">&lt;/textarea>&lt;/label>&lt;/p>
   &lt;p>&lt;label>Private Key: &lt;textarea id="private">&lt;/textarea>&lt;/label>&lt;/p>
  &lt;/fieldset>
  &lt;p>&lt;label>Input: &lt;textarea id="input">&lt;/textarea>&lt;/label>&lt;/p>
  &lt;p>&lt;button onclick="enc()">Encrypt&lt;/button> &lt;button onclick="dec()">Decrypt&lt;/button>&lt;/p>
 &lt;/body>
&lt;/html></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><pre class="no-ja-translation" data-ja-hash="12b84d4be6a7f7bdc55d6f3ea37a96b3"><span class=en-original lang=en>function handleMessage(e) {
  if (e.data == "genkeys")
    genkeys(e.port);
  else if (e.data == "encrypt")
    encrypt(e.port);
  else if (e.data == "decrypt")
    decrypt(e.port);
}

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.port.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 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><pre class="no-ja-translation" data-ja-hash="69e6e4b66305b1a92aee9fcc2372196d"><span class=en-original lang=en>onmessage = function (e) {
  var k = _generateKeyPair();
  e.port.postMessage(k[0]);
  e.port.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><pre class="no-ja-translation" data-ja-hash="efa3d6d66bd704b621cb5c4562d9a3cf"><span class=en-original lang=en>onmessage = function (e) {
  var key = e.data;
  e.port.onmessage = function (e) {
    var s = e.data;
    postMessage(_encrypt(key, s));
  }
  e.port.onclose = function (e) {
    close();
  }
}

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><pre class="no-ja-translation" data-ja-hash="854f6f4811f0f485f12e062b97d487ce"><span class=en-original lang=en>onmessage = function (e) {
  var key = e.data;
  e.port.onmessage = function (e) {
    var s = e.data;
    postMessage(_decrypt(key, s));
  }
  e.port.onclose = function (e) {
    close();
  }
}

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 class="has-ja-translation" data-ja-hash="add583522732edb8aca6202c451ddb27" data-ja-real-hash="268a742b1731b3f55fd4ab398fa56d34"><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><h3 id=conformance class="has-ja-translation" data-ja-hash="05644f41fb2fbf61aaab52464b2edf3b"><span class=en-original lang=en><span class=secno>1.3 </span>Conformance requirements</span><span class=ja-translation lang=ja><span class=secno>1.3 </span>適合性要件</span></h3>

  <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 class="no-ja-translation" data-ja-hash="6b9cae822cc27a0168c340eee0cff438"><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><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 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 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 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 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><h4 id=dependencies class="has-ja-translation" data-ja-hash="896f4eaa4f12972b56ed9cdd9a90b949"><span class=en-original lang=en><span class=secno>1.3.1 </span>Dependencies</span><span class=ja-translation lang=ja><span class=secno>1.3.1 </span>依存性</span></h4>

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

   </span><dd>
    <p class="no-ja-translation" data-ja-hash="692ef0a750fa95ddb11f05608021ff02"><span class=en-original lang=en>Many fundamental concepts from HTML5 are used by this specification.
     <a href="#refsHTML5">[HTML5]</a></span></p>

   <dt class="no-ja-translation" data-ja-hash="760145493119c1b42cb6fe0bbde08987"><span class=en-original lang=en>ECMAScript

   </span><dd>
    <p class="no-ja-translation" data-ja-hash="9fbcf32dffdec6694cf4ea145ef5db36"><span class=en-original lang=en>This specification is intended to be used with JavaScript as the
     scripting language. <a href="#refsJS">[JS]</a></span></p>

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

   </span><dd>
    <p class="no-ja-translation" data-ja-hash="f0d2498c8bb497932f36ddf86e0cf1e4"><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>
  </dl>

  <h3 id=terminology class="has-ja-translation" data-ja-hash="e182a8a3f2adf774fb1c959df71b8600"><span class=en-original lang=en><span class=secno>1.4 </span>Terminology</span><span class=ja-translation lang=ja><span class=secno>1.4 </span>用語</span></h3>

  <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 class="no-ja-translation" data-ja-hash="eb827c696acddeb1a8d0447095c94e07"><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="#refsDOM3CORE">[DOM3CORE]</a>

  </span><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><h2 id=infrastructure class="has-ja-translation" data-ja-hash="cba4f4cee5c6a3e6d8be8da68fa1234e"><span class=en-original lang=en><span class=secno>2 </span>Infrastructure</span><span class=ja-translation lang=ja><span class=secno>2 </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><h3 id=the-global class="has-ja-translation" data-ja-hash="16d7670f16b3aaf6130252e8f11702eb"><span class=en-original lang=en><span class=secno>2.1 </span>The global scope</span><span class=ja-translation lang=ja><span class=secno>2.1 </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><h4 id=the-workerglobalscope class="has-ja-translation" data-ja-hash="fe5227371e801f4ac588d0d07472a900" data-ja-real-hash="cc17376e4eee7e97d5ab420959bcac76"><span class=en-original lang=en><span class=secno>2.1.1 </span>The <code><a
   href="#workerglobalscope">WorkerGlobalScope</a></code> abstract interface</span><span class=ja-translation lang=ja><span class=secno>2.1.1 </span><code><a href="#workerglobalscope">WorkerGlobalScope</a></code> 抽象界面</span></h4>

  <pre
   class="idl no-ja-translation" data-ja-hash="330e32b358fd04f4f8631c7d12551185"><span class=en-original lang=en>interface <dfn id=workerglobalscope>WorkerGlobalScope</dfn> {
  readonly attribute <a href="#workerglobalscope">WorkerGlobalScope</a> <a href="#self" title=dom-WorkerGlobalScope-self>self</a>;
  readonly attribute <a href="#workerlocation">WorkerLocation</a> <a href="#location" title=dom-WorkerGlobalScope-location>location</a>;
  // also implements everything on <a href="#workerutils">WorkerUtils</a>

  void <a href="#close" title=dom-WorkerGlobalScope-close>close</a>();
           attribute <span>EventListener</span> <a href="#onclose" title=handler-WorkerGlobalScope-onclose>onclose</a>;
           attribute <span>EventListener</span> <a href="#onerror" title=handler-WorkerGlobalScope-onerror>onerror</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="1eaadf1fd34d0295b8799d73be1a9135"><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 class="no-ja-translation" data-ja-hash="087af626d2f79d49dcf366c0227c32c0"><span class=en-original lang=en>The <dfn id=self
   title=dom-WorkerGlobalScope-self><code>self</code></dfn> attribute must
   return the <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
   object itself.

  </span><p class="no-ja-translation" data-ja-hash="8e9bf18a7820b4401892ba71daf05527"><span class=en-original lang=en>The <dfn id=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.

  </span><hr>

  <p class="no-ja-translation" data-ja-hash="4613c16766e1a2533e8acb2824c6f9fe"><span class=en-original lang=en>When a script invokes the <dfn id=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:

  </span><ol>
   <li>
    <p class="no-ja-translation" data-ja-hash="60169fead4ccffa67d9a836cd2db0eda"><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><a
     href="#workerglobalscope">WorkerGlobalScope</a></code> object.

   </span><li>
    <p class="no-ja-translation" data-ja-hash="6243c3e4951724a3633743634fccb06e"><span class=en-original lang=en>Set the worker's <code><a
     href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
     href="#closing" title=dom-WorkerGlobalScope-closing>closing</a> flag to
     true.

   </span><li>
    <p class="no-ja-translation" data-ja-hash="facd4a44e5a83273873024773bc8359e"><span class=en-original lang=en>For each <code>MessagePort</code> object that is entangled with
     another port and that has one (but only one) port whose owner is the
     <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> object
     on which the method was invoked (this would include, for instance, the
     implicit port in used for dedicated workers), unentangle the two ports.
  </span></ol>

  <p class="no-ja-translation" data-ja-hash="3df99fd92cbc7213b4f00b8953997403"><span class=en-original lang=en>The following are the <span>event handler DOM attributes</span> that
   must be supported by objects implementing the <code><a
   href="#workerglobalscope">WorkerGlobalScope</a></code> interface:

  </span><dl>
   <dt class="no-ja-translation" data-ja-hash="96d62a92c59fca4cd2589c560425090f"><span class=en-original lang=en><dfn id=onclose
    title=handler-WorkerGlobalScope-onclose><code>onclose</code></dfn>

   </span><dd>
    <p class="has-ja-translation" data-ja-hash="91a2ce3a21f7ed687afe756baa5387d8" data-ja-real-hash="1388215c8f7c8c11b36e9c90d06b48e3"><span class=en-original lang=en>Must be invoked whenever a <code title=event-close>close</code> event
     is targeted at or bubbles through the <code><a
     href="#workerglobalscope">WorkerGlobalScope</a></code> object.

   </span><span class=ja-translation lang=ja><code title=event-close>close</code> 事象が当該 <code><a href="#workerglobalscope">WorkerGlobalScope</a></code> オブジェクトを対象としているか、泡立って当該オブジェクトを通過する時に、
呼び出されなければなりません。</span><dt class="no-ja-translation" data-ja-hash="218f1d215c51e4b4df0c668fe3526b03"><span class=en-original lang=en><dfn id=onerror
    title=handler-WorkerGlobalScope-onerror><code>onerror</code></dfn>

   </span><dd>
    <p class="has-ja-translation" data-ja-hash="72f216c6afeb138f136654f74a0585d6" data-ja-real-hash="9b3ad3aa7c6081a1e0b506a93c963c5b"><span class=en-original lang=en>Must be invoked whenever an <code title=event-error>error</code> event
     is targeted at or bubbles through the element.</span><span class=ja-translation lang=ja><code title=event-error>error</code> 事象が当該要素を対象としているか、泡立って当該要素を通過する時には、
常に呼び出されなければ<em class=rfc2119 title="MUST">なりません</em>。</span></p>

    <p class="no-ja-translation" data-ja-hash="707bda20aaa1fe8785d4a63d976c4793"><span class=en-original lang=en>The initial value of <code title=handler-WorkerGlobalScope-onerror><a
     href="#onerror">onerror</a></code> must be <code>undefined</code>.
  </span></dl>

  <h4 id=dedicated class="no-ja-translation" data-ja-hash="01e2b66319613f26fcb4ea361d2009e4"><span class=en-original lang=en><span class=secno>2.1.2 </span>Dedicated workers and the
   <code><a
   href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
   interface</span></h4>
  <!-- the XXX below is for collapsing this interface onto WorkerGlobalScope so it looks like just one interface - the inheritance is a spec fiction only -->

  <pre
   class="idl no-ja-translation" data-ja-hash="817afbdc0867386ba16e8a0ed83a2c3b"><span class=en-original lang=en>[NoInterfaceObject, XXX] interface <dfn id=dedicatedworkerglobalscope>DedicatedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
  void <a href="#postmessage" title=dom-DedicatedWorkerGlobalScope-postMessage>postMessage</a>(in any message, [Optional] in <span>MessagePort</span> messagePort);<!--
  <span>MessagePort</span> <span title="dom-DedicatedWorkerGlobalScope-startConversation">startConversation</span>(in any message);-->
           attribute <span>EventListener</span> <a href="#onmessage" title=handler-DedicatedWorkerGlobalScope-onmessage>onmessage</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="c6ea7d83d489d6962a5dafa4cb9883ac"><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 class="no-ja-translation" data-ja-hash="cd46f0a484fa815888d26bffc00cd30a"><span class=en-original lang=en>All messages received by that port must immediately be retargetted at
   the <code><a
   href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
   object.

  </span><p class="no-ja-translation" data-ja-hash="c343842e8ec7635e987fef78935dd0ae"><span class=en-original lang=en>The <dfn id=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 class="no-ja-translation" data-ja-hash="a1ce69c9e43bed80103920cd0e52253e"><span class=en-original lang=en>The following are the <span>event handler DOM attributes</span> that
   must be supported by objects implementing the <code><a
   href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
   interface:

  </span><dl>
   <dt class="no-ja-translation" data-ja-hash="160334ee188f54bd11cad6927542df5d"><span class=en-original lang=en><dfn id=onmessage
    title=handler-DedicatedWorkerGlobalScope-onmessage><code>onmessage</code></dfn>

   </span><dd>
    <p class="has-ja-translation" data-ja-hash="91a2ce3a21f7ed687afe756baa5387d8" data-ja-real-hash="693bf14ecd01b81e9953c2197c4ce97b"><span class=en-original lang=en>Must be invoked whenever a <code
     title=event-DedicatedWorkerGlobalScope-message>message</code> event is
     targeted at or bubbles through the <code><a
     href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code>
     object.
  </span><span class=ja-translation lang=ja><code title=event-DedicatedWorkerGlobalScope-message>message</code> 事象が当該 <code><a href="#dedicatedworkerglobalscope">DedicatedWorkerGlobalScope</a></code> オブジェクトを対象としているか、泡立って当該オブジェクトを通過する時に、
呼び出されなければなりません。</span></dl>

  <h4 id=shared0 class="no-ja-translation" data-ja-hash="da49a2eed6f0ff2e53a41e7fe6e36a3a"><span class=en-original lang=en><span class=secno>2.1.3 </span>Shared workers and the
   <code><a
   href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
   inteface</span></h4>
  <!-- the XXX below is for collapsing this interface onto WorkerGlobalScope so it looks like just one interface - the inheritance is a spec fiction only -->

  <pre
   class="idl no-ja-translation" data-ja-hash="26beedd870e9a7ebdb290905ca86d932"><span class=en-original lang=en>[NoInterfaceObject, XXX] interface <dfn id=sharedworkerglobalscope>SharedWorkerGlobalScope</dfn> : <a href="#workerglobalscope">WorkerGlobalScope</a> {
  readonly attribute DOMString <a href="#name" title=dom-SharedWorkerGlobalScope-name>name</a>;
           attribute <span>EventListener</span> <a href="#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 class="no-ja-translation" data-ja-hash="2cefcb206282ea1a0a38229d76567b14"><span class=en-original lang=en>The <dfn id=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">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 class="no-ja-translation" data-ja-hash="586e890e429389a63f2656c2d194935f"><span class=en-original lang=en>The following are the <span>event handler DOM attributes</span> that
   must be supported by objects implementing the <code><a
   href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
   interface:

  </span><dl>
   <dt class="no-ja-translation" data-ja-hash="bb403ab8991a4f893a1ad1d0ffad30b0"><span class=en-original lang=en><dfn id=onconnect
    title=handler-SharedWorkerGlobalScope-onconnect><code>onconnect</code></dfn>

   </span><dd>
    <p class="has-ja-translation" data-ja-hash="91a2ce3a21f7ed687afe756baa5387d8" data-ja-real-hash="848b5a001778cd88e138b16d00959122"><span class=en-original lang=en>Must be invoked whenever a <code
     title=event-SharedWorkerGlobalScope-connect>connect</code> event is
     targeted at or bubbles through the <code><a
     href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
     object.
  </span><span class=ja-translation lang=ja><code title=event-SharedWorkerGlobalScope-connect>connect</code> 事象が当該 <code><a href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code> オブジェクトを対象としているか、泡立って当該オブジェクトを通過する時に、
呼び出されなければなりません。</span></dl>

  <h3 id=base-urls class="has-ja-translation" data-ja-hash="87cf5066db3fe786def6b713cf422c90"><span class=en-original lang=en><span class=secno>2.2 </span>Base URLs and origins of
   workers</span><span class=ja-translation lang=ja><span class=secno>2.2 </span>労働者の基底 URL と起源</span></h3>

  <p class="no-ja-translation" data-ja-hash="7f0ec0a21b0d5485348f47fb8c3ac07a"><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="#location">location</a></code> attribute represents.

  </span><h3 id=the-event class="no-ja-translation" data-ja-hash="96715962ce61ea28085d7e170ec30e73"><span class=en-original lang=en><span class=secno>2.3 </span>The event loop</span></h3>

  <p class="no-ja-translation" data-ja-hash="8046b35e9604831cd24f5fd09bb3b9de"><span class=en-original lang=en>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
   object is asssociated with a <span>event loop</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">run a worker</a> algorithm.

  </span><p class="no-ja-translation" data-ja-hash="3c5a8b0b9b710969e93d11ed5ae2ce7e"><span class=en-original lang=en>Each <code><a href="#workerglobalscope">WorkerGlobalScope</a></code>
   object also has a <dfn id=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 class="no-ja-translation" data-ja-hash="f6e75a83e42204ac3c8508f490737285"><span class=en-original lang=en>Once the <code><a
   href="#workerglobalscope">WorkerGlobalScope</a></code>'s <a
   href="#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="#closing" title=dom-WorkerGlobalScope-closing>closing</a>
   flag is true, timers stop firing, notifications for all pending
   asynchronous operations are dropped, etc.

  </span><h3 id=the-workers class="has-ja-translation" data-ja-hash="b0a758845322b24463d7ebe35160f526"><span class=en-original lang=en><span class=secno>2.4 </span>The worker's ports</span><span class=ja-translation lang=ja><span class=secno>2.4 </span>労働者のポート</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 class="no-ja-translation" data-ja-hash="ccdafdb171657866dab61ba28a500549"><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-workers0>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><hr>

  <p class="no-ja-translation" data-ja-hash="26f978b46778a94d4ba398e774af8b16"><span class=en-original lang=en>A worker is said to be a <dfn id=permissible>permissible worker</dfn> if
   either:

  </span><ul>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="1408e830059dcfb69df672a38b4b1286"><span class=en-original lang=en>at some point past or present a <code>MessagePort</code> owned by the
    worker was entangled with a <code>MessagePort</code> <var
    title="">p</var> whose owner is a <code>Window</code> object whose
    <span>active document</span> is the <code>Document</code> that was that
    <span>browsing context</span>'s <span>active document</span> when <var
    title="">p</var> was created, and that <code>Document</code> is
    <span>fully active</span>, or

   </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="d7437726a136144eb08d9f005783cfee"><span class=en-original lang=en>at some point past or present a <code>MessagePort</code> owned by the
    worker was entangled with a <code>MessagePort</code> owned by another
    worker that is currently a <a href="#permissible">permissible worker</a>.
  </span></ul>

  <hr>

  <p class="has-ja-translation" data-ja-hash="236c5cb878bfd9b9303cc296c82764ac"><span class=en-original lang=en>A worker is said to be a <dfn id="en-protected">protected worker</dfn> if
   either:

  </span><span class=ja-translation lang=ja>労働者は、次のいずれかの場合、<dfn id=protected>保護労働者</dfn>であるといいます。</span><ul>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="5b3798d7af8069986d09b7dc915cbf47"><span class=en-original lang=en>it has outstanding timers, database transactions, or network
    connections, and is a <a href="#permissible">permissible worker</a>, or

   </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="d7509b8da81775bedb5ee6522497f03d"><span class=en-original lang=en>there is a <a href="#protected">protected worker</a> that at some
    point past or present owned a <code>MessagePort</code> that was entangled
    with a <code>MessagePort</code> owned by this worker.
  </span></ul>

  <hr>

  <p class="no-ja-translation" data-ja-hash="dfc82489e5358f7b62384576218af90c"><span class=en-original lang=en>A worker is said to be an <dfn id=active>active needed worker</dfn> if
   either:

  </span><ul>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="96d00b9fb7eefe6bb33e07260d2353f9"><span class=en-original lang=en>the worker is a <a href="#protected">protected worker</a>, or

   </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="2699a98205d3a6b47ed37910f9896717"><span class=en-original lang=en>at least one of the <a href="#the-workers0">the worker's ports</a> is
    entangled with a <code>MessagePort</code> <var title="">p</var> whose
    owner is a <code>Window</code> object whose <span>active document</span>
    is the <code>Document</code> that was that <span>browsing
    context</span>'s <span>active document</span> when that
    <code>MessagePort</code> <var title="">p</var> was created, and that
    <code>Document</code> is <span>fully active</span>, or

   </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="67f1204baba1d8bcbbfab28233d2b0d9"><span class=en-original lang=en>at least one of the <a href="#the-workers0">the worker's ports</a> has
    an entangled <code>MessagePort</code> owned by a <code><a
    href="#workerglobalscope">WorkerGlobalScope</a></code> object that is
    itself an <a href="#active">active needed worker</a>.
  </span></ul>

  <hr>

  <p class="no-ja-translation" data-ja-hash="7642aaede09c23a089220c1421edcbec"><span class=en-original lang=en>A worker is said to be a <dfn id=suspendable>suspendable worker</dfn> if
   it is not an <a href="#active">active needed worker</a> but either:

  </span><ul>
   <li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="960ae661864050c379756482359cf786"><span class=en-original lang=en>at least one of the <a href="#the-workers0">the worker's ports</a> has
    an entangled <code>MessagePort</code> owned by a <code>Window</code>
    object, or

   </span><li><p class="no-ja-translation ja-translation-inserted" data-ja-hash="c6381c6ecda2bf8a5113dcf88b55f65f"><span class=en-original lang=en>at least one of the <a href="#the-workers0">the worker's ports</a> has
    an entangled <code>MessagePort</code> owned by a <code><a
    href="#workerglobalscope">WorkerGlobalScope</a></code> object that is
    itself a <span>needed worker</span>.
  </span></ul>

  <h3 id=processing class="has-ja-translation" data-ja-hash="4eeffb677544f6c8799408c6b9021b4c"><span class=en-original lang=en><span class=secno>2.5 </span>Processing model</span><span class=ja-translation lang=ja><span class=secno>2.5 </span>処理モデル</span></h3>

  <p class="no-ja-translation" data-ja-hash="6c621932d8bc183c82dfb194ec31737c"><span class=en-original lang=en>When a user agent is to <dfn id=run-a>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><ol>
   <li>
    <p class="has-ja-translation" data-ja-hash="6fdced8613c508a9db62b2a4bec3fba3"><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 asychronously in that context.</span><span class=ja-translation lang=ja>完全に分離された並列の実行環境 (すなわち、別のスレッドやプロセスや等価な構造体) を作り、
その文脈で非同期にこれらの段階の残りを走らせます。</span></p>

   <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="bcdbb2d404cc07bab9cf5d4d7c39f469"><span class=en-original lang=en>If the attempt fails, then for each <code><a
     href="#worker1">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="5f99e80db6dd85e61521ca081da0a897"><span class=en-original lang=en>If the attempt succeeds, then let <var title="">source</var> be the
     text of the resource that was obtained.</span></p>
    <!-- XXX do we need
    to define character encoding decoding here? -->
    <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>
    <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="99ad90cb28611ed3165f61e920e91176"><span class=en-original lang=en>Set the <span>script's 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>

    <p class="no-ja-translation" data-ja-hash="9f54fba41a34171b216a6a1d3c585815"><span class=en-original lang=en>Create a new <span>script group</span> and add the <span
     title=concept-script>script</span> to it.</span></p>

   <li>
    <p class="no-ja-translation" data-ja-hash="f548a19eebea0d9f12ddb68a933793f7"><span class=en-original lang=en><strong>Closing orphan workers</strong>: Start monitoring the worker
     such that as soon as it stops being either an <a href="#active">active
     needed worker</a> or a <a href="#suspendable">suspendable worker</a>,
     <var title="">worker global scope</var>'s <a href="#closing"
     title=dom-WorkerGlobalScope-closing>closing</a> flag is set to true 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>
    <p class="no-ja-translation" data-ja-hash="b95907577fdce09e85f276964e7aff6b"><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="#closing" title=dom-WorkerGlobalScope-closing>closing</a> flag is
     false and the worker is a <a href="#suspendable">suspendable worker</a>,
     the user agent suspends execution of script in that worker until such
     time as either the <a href="#closing"
     title=dom-WorkerGlobalScope-closing>closing</a> flag switches to true or
     the worker stops being a <a href="#suspendable">suspendable worker</a>.</span></p>

   <li>
    <p class="no-ja-translation" data-ja-hash="80776610bb705112feb2564b4496fe2f"><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">kill a worker</a>"
     or "<a href="#terminate">terminate a worker</a>" algorithms defined
     below.</span></p>

    <p class="note no-ja-translation" data-ja-hash="76ad23661ba827d4b68ad1fc3a138902"><span class=en-original lang=en>If the script gets aborted by the "<a href="#kill-a">kill a
     worker</a>" 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 "<a
     href="#terminate">terminate a worker</a>" algorithm removes all the
     events.</span></p>

   <li>
    <p class="no-ja-translation" data-ja-hash="6e519912f34fcb58933d31516eec2c61"><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="#closing"
     title=dom-WorkerGlobalScope-closing>closing</a> flag is set to true.</span></p>

   <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="5fb6077bc30bf5b7fb16c61195f68ec4"><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">kill a worker</a>" or
     "<a href="#terminate">terminate a worker</a>" algorithms defined below.</span></p>

   <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>
    <p class="no-ja-translation" data-ja-hash="1e197805331dfc3aa6f8583697d9d623"><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="#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>
    <p class="no-ja-translation" data-ja-hash="76aff645037fb93242c0b3e0ed29b90b"><span class=en-original lang=en>Freeze the <span>script group</span>.</span></p>

    <p class="note no-ja-translation" data-ja-hash="d32bd424c711e966967069f368ca26ad"><span class=en-original lang=en>This kills timers, database transactions, etc.</span></p>

   <li>
    <p class="no-ja-translation" data-ja-hash="b39a2b11a64a8558d8c9ae5c739879a1"><span class=en-original lang=en>For each <code><a href="#worker1">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-close>close</code> at that object.</span></p>
  </ol>

  <hr>

  <p class="no-ja-translation" data-ja-hash="f73768ff3e63480f0df2f7a5a6b8f919"><span class=en-original lang=en>When a user agent is to <dfn id=kill-a>kill a worker</dfn> it must run
   the following steps in parallel with the worker's main loop (the "<a
   href="#run-a">run a worker</a>" processing model defined above):

  </span><ol>
   <li>
    <p class="no-ja-translation" data-ja-hash="a76ddc03676d95e40e0240ba3be551c8"><span class=en-original lang=en>If the worker's <code><a
     href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
     href="#closing" title=dom-WorkerGlobalScope-closing>closing</a> 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><a
     href="#workerglobalscope">WorkerGlobalScope</a></code> object.

   </span><li>
    <p class="no-ja-translation" data-ja-hash="6243c3e4951724a3633743634fccb06e"><span class=en-original lang=en>Set the worker's <code><a
     href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
     href="#closing" title=dom-WorkerGlobalScope-closing>closing</a> flag to
     true.

   </span><li>
    <p class="no-ja-translation" data-ja-hash="922d3b59e2016de5b33298ba10ada993"><span class=en-original lang=en>Wait a user-agent-defined amount of time. If the "<a href="#run-a">run
     a worker</a>" 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><li>
    <p class="no-ja-translation" data-ja-hash="e062300b1a0b646e14e0f8d084f3ab6a"><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>
     other than the <code title=event-close>close</code> event that this
     algorithm just added, discard them without processing them.

   </span><li>
    <p class="no-ja-translation" data-ja-hash="e9d30d31f5050c8a6a15b9c403a3573a"><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><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>
    <p class="has-ja-translation" data-ja-hash="6f55d58072eaadf9aaac96514d919df8"><span class=en-original lang=en>Abort the script currently running in the worker (if any script is
     running, then it will be a handler for the <code
     title=event-close>close</code> event).
  </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
(何かスクリプトが走っているとすれば、それは <code
     title=event-close>close</code>
事象の取扱器のはずです)。</span></ol>

  <p class="no-ja-translation" data-ja-hash="dbf283f17afc05f538d29f85dc0a52bf"><span class=en-original lang=en>User agents may invoke the "<a href="#kill-a">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">active needed worker</a> if the worker
   continues executing even after its <a href="#closing"
   title=dom-WorkerGlobalScope-closing>closing</a> flag was set to true.

  </span><hr>

  <p class="no-ja-translation" data-ja-hash="6e6259fd5536a6ce6726b7f1f7ec2c72"><span class=en-original lang=en>When a user agent is to <dfn id=terminate>terminate a worker</dfn> it
   must run the following steps in parallel with the worker's main loop (the
   "<a href="#run-a">run a worker</a>" processing model defined above):

  </span><ol>
   <li>
    <p class="no-ja-translation" data-ja-hash="6243c3e4951724a3633743634fccb06e"><span class=en-original lang=en>Set the worker's <code><a
     href="#workerglobalscope">WorkerGlobalScope</a></code> object's <a
     href="#closing" title=dom-WorkerGlobalScope-closing>closing</a> flag to
     true.

   </span><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>
    <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>
    <p class="no-ja-translation" data-ja-hash="ef13ce5f71f3f69e0dafefdd9f47eccc"><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></ol>

  <h4 id=runtime class="has-ja-translation" data-ja-hash="eb260f04266c3b94080b5c3f88c55a31"><span class=en-original lang=en><span class=secno>2.5.1 </span>Runtime script errors</span><span class=ja-translation lang=ja><span class=secno>2.5.1 </span>実行時スクリプト誤り</span></h4>

  <p class="no-ja-translation" data-ja-hash="8a61ca3c8edd388fa22ec61b11813a2e"><span class=en-original lang=en>Whenever a runtime script error occurs in one of the worker's scripts,
   the user agent must <span>report the error</span> using the <code
   title=handler-WorkerGlobalScope-onerror><a
   href="#onerror">onerror</a></code> <span title="event handler DOM
   attributes">event handler DOM attribute</span> of the <code><a
   href="#workerglobalscope">WorkerGlobalScope</a></code> object.

  </span><p class="no-ja-translation" data-ja-hash="60c4580e0f515ada923f347f0ae3f6c4"><span class=en-original lang=en>For shared workers, if the error is still <i title="">not handled</i>
   afterwards, the error should be reported to the user.

  </span><p class="no-ja-translation" data-ja-hash="3b0ebe7f2601491d63c8acf748ce7193"><span class=en-original lang=en>For dedicated workers, if the error is still <i title="">not handled</i>
   afterwards, <span>queue a task</span> to <a href="#fire-an">fire an error
   event</a> at the <code><a href="#worker1">Worker</a></code> object
   associated with the worker.

  </span><p class="no-ja-translation" data-ja-hash="f1840669d4137e6f15d427f7989756b6"><span class=en-original lang=en>When the user agent is to <dfn id=fire-an>fire an error event</dfn> at a
   <code><a href="#worker1">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="#message">message</a></code>, <code
   title=dom-ErrorEvent-filename><a href="#filename">filename</a></code>, and
   <code title=dom-ErrorEvent-lineno><a href="#lineno">lineno</a></code>
   attributes set appropriately. The default action of this event depends on
   whether the <code><a href="#worker1">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-an">fire
   an error event</a> at the <code><a href="#worker1">Worker</a></code>
   object associated with <em>that</em> worker. Otherwise, then the error
   should be reported to the user.

  </span><hr>

  <pre class="idl no-ja-translation" data-ja-hash="59e062a983391e726ed049c6ae57aaea"><span class=en-original lang=en>interface <dfn id=errorevent>ErrorEvent</dfn> : Event {
  readonly attribute DOMObject <a href="#message" title=dom-ErrorEvent-message>message</a>;
  readonly attribute DOMObject <a href="#filename" title=dom-ErrorEvent-filename>filename</a>;
  readonly attribute unsigned long <a href="#lineno" title=dom-ErrorEvent-lineno>lineno</a>;
  void <a href="#initerrorevent" title=dom-ErrorEvent-initErrorEvent>initErrorEvent</a>(in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMObject messageArg, in DOMObject filenameArg, in unsigned long linenoArg);
  void <a href="#initerroreventns" title=dom-ErrorEvent-initErrorEventNS>initErrorEventNS</a>(in DOMString namespaceURIArg, in DOMString typeArg, in boolean canBubbleArg, in boolean cancelableArg, in DOMObject messageArg, in DOMObject filenameArg, in unsigned long linenoArg);
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="9d43314493123a2b2149ea035cc1b572"><span class=en-original lang=en>The <dfn id=initerrorevent
   title=dom-ErrorEvent-initErrorEvent><code>initErrorEvent()</code></dfn>
   and <dfn id=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 DOM3 Events interfaces. <a
   href="#refsDOM3EVENTS">[DOM3EVENTS]</a>

  </span><p class="no-ja-translation" data-ja-hash="7d24fa221c135ec2b437946226400737"><span class=en-original lang=en>The <dfn id=message
   title=dom-ErrorEvent-message><code>message</code></dfn> attribute
   represents the error message.

  </span><p class="no-ja-translation" data-ja-hash="47c39cbddc08e2a5d463cd6e0a27d4b7"><span class=en-original lang=en>The <dfn id=filename
   title=dom-ErrorEvent-filename><code>filename</code></dfn> attribute
   represents the <span>absolute URL</span> of the script in which the error
   originally occured.

  </span><p class="no-ja-translation" data-ja-hash="8f00dc144763f529c193251c4ae6579e"><span class=en-original lang=en>The <dfn id=lineno title=dom-ErrorEvent-lineno><code>lineno</code></dfn>
   attribute represents the line number where the error occured in the
   script.

  </span><h3 id=creating class="has-ja-translation" data-ja-hash="f0a4732d38d01e3d103b68468f9fe234"><span class=en-original lang=en><span class=secno>2.6 </span>Creating workers</span><span class=ja-translation lang=ja><span class=secno>2.6 </span>労働者の作成</span></h3>

  <h4 id=the-abstractworker class="has-ja-translation" data-ja-hash="fe5227371e801f4ac588d0d07472a900" data-ja-real-hash="9a7040b26903cb67873e70582b2e3a5b"><span class=en-original lang=en><span class=secno>2.6.1 </span>The <code><a
   href="#abstractworker">AbstractWorker</a></code> abstract interface</span><span class=ja-translation lang=ja><span class=secno>2.6.1 </span><code><a href="#abstractworker">AbstractWorker</a></code> 抽象界面</span></h4>

  <pre class="idl no-ja-translation" data-ja-hash="c9e3c7c45c089ab5b21145c0aa2fb17e"><span class=en-original lang=en>interface <dfn id=abstractworker>AbstractWorker</dfn> {
           attribute <span>EventListener</span> <a href="#onerror0" title=handler-AbstractWorker-onerror>onerror</a>;
           attribute <span>EventListener</span> <a href="#onclose0" title=handler-AbstractWorker-onclose>onclose</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="e39a76d762bfd9fb1a4ef6442ded36b3"><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 class="no-ja-translation" data-ja-hash="4f7356effb9eccb6268b11a363b0c51d"><span class=en-original lang=en>The following are the <span>event handler DOM attributes</span> that
   must be supported by objects implementing the <code><a
   href="#abstractworker">AbstractWorker</a></code> interface:

  </span><dl>
   <dt class="no-ja-translation" data-ja-hash="9271e517353d64116733d90133259cae"><span class=en-original lang=en><dfn id=onerror0
    title=handler-AbstractWorker-onerror><code>onerror</code></dfn>

   </span><dd>
    <p class="no-ja-translation" data-ja-hash="3998f6cd6a9193846f5e07b04202500c"><span class=en-original lang=en>Must be invoked whenever an <code title=event-error>error</code> event
     is targeted at or bubbles through the <code><a
     href="#abstractworker">AbstractWorker</a></code> object.

   </span><dt class="no-ja-translation" data-ja-hash="a66f8d800a45cc2273dc71888c78ecd0"><span class=en-original lang=en><dfn id=onclose0
    title=handler-AbstractWorker-onclose><code>onclose</code></dfn>

   </span><dd>
    <p class="no-ja-translation" data-ja-hash="90325fa5f5171b4f558eabaeac83bba8"><span class=en-original lang=en>Must be invoked whenever an <code title=event-close>close</code> event
     is targeted at or bubbles through the <code><a
     href="#abstractworker">AbstractWorker</a></code> object.
  </span></dl>

  <h4 id=dedicated0 class="no-ja-translation" data-ja-hash="a19aaade72c8a5d27a02c8d16642f277"><span class=en-original lang=en><span class=secno>2.6.2 </span>Dedicated workers and the
   <code><a href="#worker1">Worker</a></code> interface</span></h4>

  <pre
   class="idl no-ja-translation" data-ja-hash="08be78e654148934db6ca23bc36fa7f6"><span class=en-original lang=en>[<a href="#worker2" title=dom-Worker>Constructor</a>(in DOMString scriptURL)]
interface <dfn id=worker1>Worker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
  void <a href="#terminate0" title=dom-Worker-terminate>terminate</a>();

  void <a href="#postmessage0" title=dom-Worker-postMessage>postMessage</a>(in any message, [Optional] in <span>MessagePort</span> messagePort);<!--
  <span>MessagePort</span> <span title="dom-Worker-startConversation">startConversation</span>(in any message);-->
           attribute <span>EventListener</span> <a href="#onmessage0" title=handler-Worker-onmessage>onmessage</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="de30b8d41bcd89009d2aef1d62ea0b46"><span class=en-original lang=en>The <dfn id=terminate0
   title=dom-Worker-terminate><code>terminate()</code></dfn> method, when
   invoked, must cause the "<a href="#terminate">terminate a worker</a>"
   algorithm to be run on the worker with with the object is associated.

  </span><p class="no-ja-translation" data-ja-hash="5bc910b7c194db663b68f5a7d4c10a61"><span class=en-original lang=en><code><a href="#worker1">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="#worker1">Worker</a></code> object.

  </span><p class="no-ja-translation" data-ja-hash="6913e4a1e1b8f864b65900e6b4f480ed"><span class=en-original lang=en>All messages received by that port must immediately be retargetted at
   the <code><a href="#worker1">Worker</a></code> object.

  </span><p class="no-ja-translation" data-ja-hash="5e032d219f702b8b96f218aacfba4c26"><span class=en-original lang=en>The <dfn id=postmessage0
   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="#worker1">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 class="no-ja-translation" data-ja-hash="e5b4a11fecaff5acef7e63837606f9a6"><span class=en-original lang=en>The following are the <span>event handler DOM attributes</span> that
   must be supported by objects implementing the <code><a
   href="#worker1">Worker</a></code> interface:

  </span><dl>
   <dt class="no-ja-translation" data-ja-hash="1e7efb7f0b77ed1e6f543f6c9cc3387e"><span class=en-original lang=en><dfn id=onmessage0
    title=handler-Worker-onmessage><code>onmessage</code></dfn>

   </span><dd>
    <p class="has-ja-translation" data-ja-hash="91a2ce3a21f7ed687afe756baa5387d8" data-ja-real-hash="c68f92321aa3d122a0022259f645a1d2"><span class=en-original lang=en>Must be invoked whenever a <code
     title=event-Worker-message>message</code> event is targeted at or
     bubbles through the <code><a href="#worker1">Worker</a></code> object.
  </span><span class=ja-translation lang=ja><code title=event-Worker-message>message</code> 事象が当該 <code><a href="#worker1">Worker</a></code> オブジェクトを対象としているか、泡立って当該オブジェクトを通過する時に、
呼び出されなければなりません。</span></dl>

  <hr>

  <p class="no-ja-translation" data-ja-hash="82fcc98f85490bca63805a347135340d"><span class=en-original lang=en>When the <dfn id=worker2 title=dom-Worker><code>Worker(<var
   title="">scriptURL</var>)</code></dfn> constructor is invoked, the user
   agent must run the following steps:

  </span><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>
    <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>
    <p class="no-ja-translation" data-ja-hash="b087dd24bd7b57655bef9f719db30b9a"><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
     script that invoked the constructor, then throw a <span>security
     exception</span>.

   </span><li>
    <p class="no-ja-translation" data-ja-hash="1b3db8a7e7ece473ac900f50243dc62c"><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>
    <p class="no-ja-translation" data-ja-hash="ed81333a6158bdeffac41bdff6ec3c5a"><span class=en-original lang=en>Create a new <code><a href="#worker1">Worker</a></code> object,
     associated with <var title="">worker global scope</var>. Let <var
     title="">worker</var> be this new object.

   </span><li>
    <p class="no-ja-translation" data-ja-hash="07cc057567324a83e25ec6344dc011a7"><span class=en-original lang=en><span>Create a <code>MessagePort</code> object</span> owned by the
     <span>script execution context</span> of the script that invoked the
     method. Let this be the <var title="">outside port</var>.

   </span><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>
    <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>
    <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>
    <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>
    <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>
    <p class="has-ja-translation" data-ja-hash="faa1ae1399f8e4f6b212fe45bba07893"><span class=en-original lang=en>Open <var title="">inside port</var>'s <span>port message
     queue</span>.

   </span><span class=ja-translation lang=ja><var title="">inside port</var> の<span>ポート・メッセージ待ち行列</span>を開きます。</span><li>
    <p class="has-ja-translation" data-ja-hash="5eaa92a75cbbf580809052327262059a"><span class=en-original lang=en>Open <var title="">outside port</var>'s <span>port message
     queue</span>.

   </span><span class=ja-translation lang=ja><var title="">outside port</var> の<span>ポート・メッセージ待ち行列</span>を開きます。</span><li>
    <p class="no-ja-translation" data-ja-hash="13490b80df7f929a817aaedc342318df"><span class=en-original lang=en><a href="#run-a">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>
  </ol>

  <h4 id=shared1 class="no-ja-translation" data-ja-hash="660755479f7743bee608286560e94bfd"><span class=en-original lang=en><span class=secno>2.6.3 </span>Shared workers and the
   <code><a href="#sharedworker">SharedWorker</a></code> interface</span></h4>

  <pre
   class="idl no-ja-translation" data-ja-hash="4efb684ac777c7e96a11f4ef746c6b8a"><span class=en-original lang=en>[<a href="#sharedworker0" title=dom-SharedWorker>Constructor</a>(in DOMString scriptURL, in DOMString name)]
interface <dfn id=sharedworker>SharedWorker</dfn> : <a href="#abstractworker">AbstractWorker</a> {
  readonly attribute <span>MessagePort</span> <a href="#port" title=dom-SharedWorker-port>port</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="fa90f278bf10ccc803f16340cb3454f3"><span class=en-original lang=en>The <dfn id=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 class="no-ja-translation" data-ja-hash="ec56f4c5071ac285686586d381295796"><span class=en-original lang=en>When the <dfn id=sharedworker0
   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><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>
    <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>
    <p class="no-ja-translation" data-ja-hash="b087dd24bd7b57655bef9f719db30b9a"><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
     script that invoked the constructor, then throw a <span>security
     exception</span>.

   </span><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="2800d1a8667906afc331a67e21d9ea29"><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>
      <p class="no-ja-translation" data-ja-hash="07cc057567324a83e25ec6344dc011a7"><span class=en-original lang=en><span>Create a <code>MessagePort</code> object</span> owned by the
       <span>script execution context</span> of the script that invoked the
       method. Let this be the <var title="">outside port</var>.

     </span><li>
      <p class="no-ja-translation" data-ja-hash="95cd5e27932141432ed9ff6323032568"><span class=en-original lang=en>Assign <var title="">outside port</var> to the <code
       title=dom-SharedWorker-port><a href="#port">port</a></code> attribute
       of <var title="">worker</var>.

     </span><li>
      <p class="no-ja-translation" data-ja-hash="5aec0369bd40bfd0f0ff2dc70f75b9f5"><span class=en-original lang=en>If there exists a <code><a
       href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
       object whose <a href="#closing"
       title=dom-WorkerGlobalScope-closing>closing</a> flag is false, whose
       <code title=dom-WorkerGlobalScope-name>name</code> attribute is
       exactly equal to the <var title="">name</var> argument, and whose
       <code title=dom-WorkerGlobalScope-location><a
       href="#location">location</a></code> attribute represents an
       <span>absolute URL</span> that has the <span>same origin</span> as the
       resulting <span>absolute URL</span>, then run these substeps:</span></p>

      <ol>
       <li>
        <p class="no-ja-translation" data-ja-hash="826754f668578065470b1f9de24553bc"><span class=en-original lang=en>Let <var title="">worker global scope</var> be that <code><a
         href="#sharedworkerglobalscope">SharedWorkerGlobalScope</a></code>
         object.

       </span><li>
        <p class="no-ja-translation" data-ja-hash="7b6f8fa4ae92ed20dd16a2fb90c3e618"><span class=en-original lang=en>If <var title="">worker global scope</var>'s <code
         title=dom-WorkerGlobalScope-location><a
         href="#location">location</a></code> attribute represents an
         <span>absolute URL</span> that is not exactly equal to the resulting
         <span>absolute URL</span>, then throw a
         <code>URL_MISMATCH_ERR</code> exception and abort all these steps.
         <span class=big-issue>code 21</span>

       </span><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>
        <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>
        <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>
        <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>
        <p class="no-ja-translation" data-ja-hash="59d27c5ea77ba33df367bcf4df580a15"><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 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-messagePort>messagePort</code> attribute
         whose value is the newly created port, and <span>queue a task</span>
         to dispatch the event at <var title="">worker global scope</var>.

       </span><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></ol>

     <li>
      <p class="no-ja-translation" data-ja-hash="3431d32f7d58431abbb9fd0e6f63d6a1"><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>
      <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>
      <p class="no-ja-translation" data-ja-hash="c285d8b77f24f839bfaaa69b872159c8"><span class=en-original lang=en>Set the <code title=dom-SharedWorkerGlobalScope-name><a
       href="#name">name</a></code> attribute of <var title="">worker global
       scope</var> to <var title="">name</var>.

     </span><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>
      <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></ol>

   <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>
    <p class="no-ja-translation" data-ja-hash="59d27c5ea77ba33df367bcf4df580a15"><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 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-messagePort>messagePort</code> attribute whose
     value is the newly created port, and <span>queue a task</span> to
     dispatch the event at <var title="">worker global scope</var>.

   </span><li>
    <p class="no-ja-translation" data-ja-hash="13490b80df7f929a817aaedc342318df"><span class=en-original lang=en><a href="#run-a">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>
  </ol>

  <h2 id=apis-available class="has-ja-translation" data-ja-hash="4fce100e6a2eccbb2df8631a438feeb6"><span class=en-original lang=en><span class=secno>3 </span>APIs available to workers</span><span class=ja-translation lang=ja><span class=secno>3 </span>労働者が利用可能な API</span></h2>
  <!-- the XXX below is for collapsing this interface onto WorkerGlobalScope so it looks like just one interface - the inheritance is a spec fiction only -->

  <pre
   class="idl no-ja-translation" data-ja-hash="de67fcab71c76bc7696cdd5e898a653e"><span class=en-original lang=en>[NoInterfaceObject, ImplementedOn=WorkerGlobalScope, XXX] interface <dfn id=workerutils>WorkerUtils</dfn> {
  void <a href="#importscripts" title=dom-WorkerGlobalScope-importScripts>importScripts</a>([Variadic] in DOMString urls);
  readonly attribute <span>Storage</span> <a href="#localstorage" title=dom-localStorage>localStorage</a>;
  readonly attribute <a href="#navigator0">Navigator</a> <a href="#navigator" title=dom-navigator>navigator</a>;
  <span>Database</span> <a href="#opendatabase" title=dom-opendatabase>openDatabase</a>(in DOMString name, in DOMString version, in DOMString displayName, in unsigned long estimatedSize);<!--
  void <span title="dom-showNotification">showNotification</span>(in DOMString title, in DOMString subtitle, in DOMString description, [Optional] in VoidCallback onclick); XXX-NOTIFY -->
};</span></pre>

  <p class="has-ja-translation" data-ja-hash="fc1e0d30e2c0869e54fb2487a7dd6836" data-ja-real-hash="43ee0f4f7856a9484e5ed892bc4ab914"><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 class="no-ja-translation" data-ja-hash="ee5c969b7e5c71d39f0fe9919b1173fe"><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 class="big-issue no-ja-translation" data-ja-hash="fffa5f76ab27c1602edf28b5c8fbcc6d"><span class=en-original lang=en>Need to define a sync database API.</span></p>
  <!-- XXX ApplicationCache -->
  <!-- XXX a way to set cookies on the URL for the script -->
  <!-- XXX debugging: void log(in DOMString s); // log to console -->
  <!-- XXX debugging: onerror -->

  <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><h3 id=importing class="has-ja-translation" data-ja-hash="e7522d998689dc52be80feeff81470ca"><span class=en-original lang=en><span class=secno>3.1 </span>Importing scripts and
   libraries</span><span class=ja-translation lang=ja><span class=secno>3.1 </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="a50ee5d5d404f735326c6d0cb9ede11c"><span class=en-original lang=en>When a script invokes the <dfn id=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><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>
    <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>
    <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>
    <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="d6801f59b2563b0c5b83889b85620faa"><span class=en-original lang=en>If the fetching attempt succeeded, then let <var
       title="">source</var> be the text of the resource that was obtained,
       and 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>
      <p class="no-ja-translation" data-ja-hash="cf414ab741fec06cd9788dadd0849790"><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">run a worker</a> algorithm.</span></p>

      <p class="no-ja-translation" data-ja-hash="c33e5168b4feb73106bd20c058fe035e"><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">kill a
       worker</a>" or "<a href="#terminate">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="c7d543d741a3d731cce1fac38ebfcb64"><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="#importscripts">importScripts()</a></code> method.</span></p>

      <p class="no-ja-translation" data-ja-hash="468ae33f57bcaf9bf43e2113273491a6"><span class=en-original lang=en>If the "<a href="#kill-a">kill a worker</a>" or "<a
       href="#terminate">terminate a worker</a>" algorithms abort the script
       then abort all these steps.</span></p>
    </ol>
  </ol>

  <h3 id=the-navigator class="no-ja-translation" data-ja-hash="920dd52a11144ff4776fa357ce6245e1"><span class=en-original lang=en><span class=secno>3.2 </span>The <code><a
   href="#navigator0">Navigator</a></code> object</span></h3>

  <p class="no-ja-translation" data-ja-hash="2affbf4546661b0d28c37da361b1cf65"><span class=en-original lang=en>The <dfn id=navigator title=dom-navigator><code>navigator</code></dfn>
   attribute of the <code><a href="#workerutils">WorkerUtils</a></code>
   interface must return an instance of the <code><a
   href="#navigator0">Navigator</a></code> interface, which represents the
   identity and state of the user agent (the client):

  </span><pre class="idl no-ja-translation" data-ja-hash="acb6d94ad25eb722cedfe999a7579982"><span class=en-original lang=en>interface <dfn id=navigator0>Navigator</dfn> {
  // objects implementing this interface also implement the interfaces listed below
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="cc1c14039bdbf516ffffc18ed475544f"><span class=en-original lang=en>Objects implementing the <code><a
   href="#navigator0">Navigator</a></code> interface must also implement the
   <span>NavigatorID</span> and <span>NavigatorOnLine</span> interfaces
   specified in the HTML5 specification. <a href="#refsHTML5">[HTML5]</a>

  </span><p class="note no-ja-translation" data-ja-hash="0b5a83138f5e72c3cbeff9a2b59e9920"><span class=en-original lang=en>The <code><a href="#navigator0">Navigator</a></code>
   interface defined in this specification is different than the one defined
   in the HTML5 specification.

  </span><h3 id=apis-defined class="has-ja-translation" data-ja-hash="d6d6885373ce92bfa8857f5a375a9c8f"><span class=en-original lang=en><span class=secno>3.3 </span>APIs defined in other
   specifications</span><span class=ja-translation lang=ja><span class=secno>3.3 </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="3c9a0dcc3dbfc7283eea34202de4d321"><span class=en-original lang=en>The <dfn id=localstorage
   title=dom-localStorage><code>localStorage</code></dfn>, <dfn
   id=opendatabase title=dom-opendatabase><code>openDatabase()</code></dfn>
   must act as defined for the APIs with the same names on the
   <code>Window</code> object in the HTML5 specification, with the exception
   that where the API would use the <span>origin</span> of the <span>active
   document</span> of the <span>browsing context</span> of the
   <code>Window</code> object on which the method was supposedly invoked, it
   must instead use the <span>origin</span> of the script that invoked the
   method. <a href="#refsHTML5">[HTML5]</a>

  </span><p class="no-ja-translation" data-ja-hash="6563db877bfe3b57772fed7dedbfc84b"><span class=en-original lang=en>The <dfn id=shownotification
   title=dom-showNotification><code>showNotification()</code></dfn> methods
   must act as defined for the APIs with the same names on the
   <code>Window</code> object in the HTML5 specification. <a
   href="#refsHTML5">[HTML5]</a>

  </span><h3 id=interface class="has-ja-translation" data-ja-hash="78e75b89c304218ef77a66cd9efdf398"><span class=en-original lang=en><span class=secno>3.4 </span>Interface objects and
   constructors</span><span class=ja-translation lang=ja><span class=secno>3.4 </span>界面オブジェクトと構築器</span></h3>

  <p class="no-ja-translation" data-ja-hash="2135421a70c368c728d0af40f99cee55"><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><ul>
   <li>
    <p class="no-ja-translation" data-ja-hash="ee396bbb3d32ae2d31fc0a108ea3389c"><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. <a
     href="#refsXHR">[XHR]</a>

   </span><li>
    <p class="has-ja-translation" data-ja-hash="3a205f7812c3029dcecfcbbd61199f90"><span class=en-original lang=en>The <code>WebSocket</code> interface object and constructor.

   </span><span class=ja-translation lang=ja><code>WebSocket</code> 界面オブジェクトと構築器</span><li>
    <p class="has-ja-translation" data-ja-hash="c537145c77e1103c3a76557f40172a5a"><span class=en-original lang=en>The <code>MessageChannel</code> interface object and constructor.

   </span><span class=ja-translation lang=ja><code>MessageChannel</code> 界面オブジェクトと構築器</span><li>
    <p class="no-ja-translation" data-ja-hash="0b577152dfe727cea2b187ff18e26a57"><span class=en-original lang=en>The <code title=dom-Worker><a href="#worker2">Worker()</a></code> and
     <code title=dom-SharedWorker><a href="#sharedworker0">SharedWorker(<var
     title="">url</var>)</a></code> constructors.
  </span></ul>

  <h3 id=worker0 class="has-ja-translation" data-ja-hash="ae4aa0f882fcbd2ee8252e59113ec205"><span class=en-original lang=en><span class=secno>3.5 </span>Worker locations</span><span class=ja-translation lang=ja><span class=secno>3.5 </span>労働者の所在</span></h3>

  <pre class="idl no-ja-translation" data-ja-hash="235fe0311fd11c41ec8ff0242ac64521"><span class=en-original lang=en>interface <dfn id=workerlocation>WorkerLocation</dfn> {
  readonly attribute DOMString <a href="#href" title=dom-WorkerLocation-href>href</a>;
  readonly attribute DOMString <a href="#protocol" title=dom-WorkerLocation-protocol>protocol</a>;
  readonly attribute DOMString <a href="#host" title=dom-WorkerLocation-host>host</a>;
  readonly attribute DOMString <a href="#hostname" title=dom-WorkerLocation-hostname>hostname</a>;
  readonly attribute DOMString <a href="#port0" title=dom-WorkerLocation-port>port</a>;
  readonly attribute DOMString <a href="#pathname" title=dom-WorkerLocation-pathname>pathname</a>;
  readonly attribute DOMString <a href="#search" title=dom-WorkerLocation-search>search</a>;
  readonly attribute DOMString <a href="#hash" title=dom-WorkerLocation-hash>hash</a>;
};</span></pre>

  <p class="no-ja-translation" data-ja-hash="36debbc2eb6f1156c1bae8ade6331936"><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 class="no-ja-translation" data-ja-hash="2d034b308d5fd16e5cf88da132b7ecb7"><span class=en-original lang=en>The <dfn id=href title=dom-WorkerLocation-href><code>href</code></dfn>
   attribute must return the <span>absolute URL</span> that the object
   represents.

  </span><p class="no-ja-translation" data-ja-hash="f2d3c1ea8523c84f8de83e432d4ecb8e"><span class=en-original lang=en>The <code><a href="#workerlocation">WorkerLocation</a></code> interface
   also has the complement of <span>URL decomposition attributes</span>, <dfn
   id=protocol title=dom-WorkerLocation-protocol><code>protocol</code></dfn>,
   <dfn id=host title=dom-WorkerLocation-host><code>host</code></dfn>, <dfn
   id=port0 title=dom-WorkerLocation-port><code>port</code></dfn>, <dfn
   id=hostname title=dom-WorkerLocation-hostname><code>hostname</code></dfn>,
   <dfn id=pathname
   title=dom-WorkerLocation-pathname><code>pathname</code></dfn>, <dfn
   id=search title=dom-WorkerLocation-search><code>search</code></dfn>, and
   <dfn id=hash title=dom-WorkerLocation-hash><code>hash</code></dfn>. These
   must follow the rules given for URL decomposition 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="#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><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>

  <p class="big-issue no-ja-translation" data-ja-hash="683a8b064076b13e2c36958afe8b9897"><span class=en-original lang=en>This section will be written in a future
   draft.<!--XXX-->

  </span><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="652eb8d20b353fa25a4dac94db2c5839"><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, 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, 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 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>