[1] [CITE[B 互換性 (Compatibility)]] ([TIME[2002-07-19 22:24:55 +09:00]] 版) <http://www2u.biglobe.ne.jp/~oz-07ams/prog/ecma262r3/B_Compatibility.html#section-B.1.2>

[2] >>1 に従えば \069 みたいなのは八進数のエスケープではないことになってしまいますが、
ブラウザで試してみると \06 + 文字 9 として処理されます。

[3] 
() が8個ないときの \8 の解釈

<http://software.hixie.ch/utilities/js/live-dom-viewer/?%3Cscript%3E%0Aif%20(%22%5Cx08%22.match%20(%2F%5C8%2F))%20%7B%0A%20%20document.write%20(%22U%2B0008%22)%3B%0A%7D%20else%20if%20(%228%22.match%20(%2F%5C8%2F))%20%7B%0A%20%20document.write%20(%22U%2B0038%20DIGIT%20EIGHT%22)%3B%0A%7D%20else%20if%20(%22%5C%5C8%22.match%20(%2F%5C8%2F))%20%7B%0A%20%20document.write%20(%22U%2B005C%20REVERSE%20SOLIDUS%2C%20U%2B0038%20DIGIT%20EIGHT%22)%3B%0A%7D%20else%20%7B%0A%20%20document.write%20(%22Unknown%22)%3B%0A%7D%0A%3C%2Fscript%3E>

[[WinIE 7]]、[[Safari]]、[[Chrome]]: [CODE(char)[[[U+0038]]]] [CODE(charname)@en[[[DIGIT EIGHT]]]]

[[Opera]] 9.61: [CODE(char)[[[U+0008]]]]

[[Firefox]] 3: [CODE(char)[[[U+005C]]]] [CODE(charname)@en[[[REVERSE SOLIDUS]]]],
[CODE(char)[[[U+0038]]]] [CODE(charname)@en[[[DIGIT EIGHT]]]]

[4] [[文字列リテラル]]での \8 の解釈

<http://software.hixie.ch/utilities/js/live-dom-viewer/?%3Cscript%3E%0D%0Adocument.write%20(encodeURIComponent%20(%22%5C8%22))%3B%0D%0A%3C%2Fscript%3E>

どのブラウザでも [CODE(char)[[[U+0038]]]] [CODE(charname)@en[[[DIGIT EIGHT]]]]