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<!DOCTYPE html>
<html class="split chapter"><head><meta charset="utf-8"><title>Annex B (informative) Compatibility # Ⓣ Ⓔ ① Ⓐ — Annotated ES5</title><link rel="stylesheet" href="style.css"><link href="A.html" title="Annex A (informative) Grammar Summary " rel="prev">
<link href="spec.html" title="TOC" rel="index">
<link href="C.html" title="Annex C (informative) The Strict Mode of ECMAScript " rel="next">
</head><body><div class="head">
<h2 id="top">Annotated ECMAScript 5.1 <span id="timestamp"></span></h2>
<div id="mascot-treehouse">
<img id="mascot" align="left" src="js-mascot.svg" alt=""><img id="bubble" src="bubble.svg" alt=""></div>
<p id="slogan">‟Ex igne vita”</p>
<div id="annotations"></div>
<script src="timestamp.js"></script></div>
<nav>
<a href="A.html">← Annex A (informative) Grammar Summary </a> –
<a href="spec.html" class="toc-nav">TOC</a> –
<a href="C.html">Annex C (informative) The Strict Mode of ECMAScript →</a>
<ol class="toc"><li><a href="B.html#B" id="B-toc">Annex B (informative) Compatibility</a>
<b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> <ol><li><a href="B.html#B.1" id="B.1-toc">B.1 Additional Syntax</a>
<b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> <ol><li><a href="B.html#B.1.1" id="B.1.1-toc">B.1.1 Numeric Literals</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> </li><li><a href="B.html#B.1.2" id="B.1.2-toc">B.1.2 String Literals</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> </li></ol></li><li><a href="B.html#B.2" id="B.2-toc">B.2 Additional Properties</a>
<b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> <ol><li><a href="B.html#B.2.1" id="B.2.1-toc">B.2.1 escape (string)</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> </li><li><a href="B.html#B.2.2" id="B.2.2-toc">B.2.2 unescape (string)</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> </li><li><a href="B.html#B.2.3" id="B.2.3-toc">B.2.3 String.prototype.substr (start, length)</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> </li><li><a href="B.html#B.2.4" id="B.2.4-toc">B.2.4 Date.prototype.getYear ( )</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> </li><li><a href="B.html#B.2.5" id="B.2.5-toc">B.2.5 Date.prototype.setYear (year)</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> </li><li><a href="B.html#B.2.6" id="B.2.6-toc">B.2.6 Date.prototype.toGMTString ( )</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b> </li></ol></li></ol></li></ol></nav>
<h2 id="B">Annex B (informative) Compatibility <a href="#B">#</a> <a href="#B-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h2>
<h3 id="B.1">B.1 Additional Syntax <a href="#B.1">#</a> <a href="#B.1-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h3>
<p>
Past
editions of ECMAScript have included additional syntax and semantics
for specifying octal literals and octal escape sequences. These have
been removed from this edition of ECMAScript. This non-normative
annex presents uniform syntax and semantics for octal literals and
octal escape sequences for compatibility with some older ECMAScript
programs.</p>
<h4 id="B.1.1">B.1.1 Numeric Literals <a href="#B.1.1">#</a> <a href="#B.1.1-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h4>
<p>
The
syntax and semantics of <a href="x7.html#x7.8.3">7.8.3</a> can be extended as follows except that
this extension is not allowed for <a href="x10.html#x10.1.1" class="term-ref">strict mode code</a>:</p>
<p class="tiny-btm">
<b>Syntax</b></p>
<p class="keep">
<i>NumericLiteral </i><b>::</b></p>
<p class="def1-btm">
<i>DecimalLiteral<br>HexIntegerLiteral<br>OctalIntegerLiteral</i></p>
<p class="keep">
<i>OctalIntegerLiteral </i><b>::</b></p>
<p class="def1-btm">
<code><b>0</b></code> <i>OctalDigit<br>OctalIntegerLiteral OctalDigit</i></p>
<p class="keep">
<i>OctalDigit </i><b>::</b> <b>one
of</b></p>
<p class="def1-btm">
<code><b>0</b></code> <i><b>
</b></i><code><b>1</b></code> <i><b>
</b></i><code><b>2</b></code> <i><b>
</b></i><code><b>3
</b></code> <i> </i><code><b>4
</b></code> <i> </i><code><b>5</b></code> <i><b>
</b></i><code><b>6</b></code> <i><b>
</b></i><code><b>7</b></code></p>
<p>
Semantics</p>
<ul><li><p>
The
MV of <i>NumericLiteral</i>
<b>::</b>
<i>OctalIntegerLiteral</i> is
the MV of <i>OctalIntegerLiteral</i>.</p>
</li>
<li><p>
The
MV of <i>OctalDigit</i> <b>::</b>
<code><b>0</b></code>
is 0.</p>
</li>
<li><p>
The
MV of <i>OctalDigit</i> <b>::</b>
<code><b>1</b></code>
is 1.</p>
</li>
<li><p>
The
MV of <i>OctalDigit</i> <b>::</b>
<code><b>2</b></code>
is 2.</p>
</li>
<li><p>
The
MV of <i>OctalDigit</i> <b>::</b>
<code><b>3</b></code>
is 3.</p>
</li>
<li><p>
The
MV of <i>OctalDigit</i> <b>::</b>
<code><b>4</b></code>
is 4.</p>
</li>
<li><p>
The
MV of <i>OctalDigit</i> <b>::</b>
<code><b>5</b></code>
is 5.</p>
</li>
<li><p>
The
MV of <i>OctalDigit</i> <b>::</b>
<code><b>6</b></code>
is 6.</p>
</li>
<li><p>
The
MV of <i>OctalDigit</i> <b>::</b>
<code><b>7</b></code>
is 7.</p>
</li>
<li><p>
The
MV of <i>OctalIntegerLiteral </i><b>::</b>
<code><b>0</b></code>
<i>OctalDigit</i> is the MV
of <i>OctalDigit</i>.</p>
</li>
<li><p>
The
MV of <i>OctalIntegerLiteral </i><b>::</b>
<i>OctalIntegerLiteral</i>
<i>OctalDigit</i> is (the MV
of <i>OctalIntegerLiteral</i>
times 8) plus the MV of <i>OctalDigit</i>.</p>
</li></ul><h4 id="B.1.2">B.1.2 String Literals <a href="#B.1.2">#</a> <a href="#B.1.2-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h4>
<p>
The
syntax and semantics of <a href="x7.html#x7.8.4">7.8.4</a> can be extended as follows except that
this extension is not allowed for <a href="x10.html#x10.1.1" class="term-ref">strict mode code</a>:</p>
<p class="tiny-btm">
<b>Syntax</b></p>
<p class="keep">
<i>EscapeSequence </i><b>::</b></p>
<p class="def1-btm">
<i>CharacterEscapeSequence<br>OctalEscapeSequence<br>HexEscapeSequence<br>UnicodeEscapeSequence</i></p>
<p class="keep">
<i>OctalEscapeSequence </i><b>::</b></p>
<p class="def1-btm">
<i>OctalDigit </i>[<a href="x5.html#lookahead-not-in">lookahead
<span class="symbol">∉</span></a>
<i>DecimalDigit</i>]<i><br>ZeroToThree
OctalDigit </i>[<a href="x5.html#lookahead-not-in">lookahead
<span class="symbol">∉</span></a><i>DecimalDigit</i>]<i><br>FourToSeven
OctalDigit<br>ZeroToThree OctalDigit OctalDigit</i></p>
<p class="keep">
<i>ZeroToThree </i><b>::</b> <b>one
of</b></p>
<p class="def1-btm">
<code><b>0
1 2 3</b></code></p>
<p class="keep">
<i>FourToSeven </i><b>::</b><i><b>
</b></i><b>one
of</b></p>
<p class="def1-btm">
<b>4
5 6 7</b></p>
<p class="tiny-btm">
<b>Semantics</b></p>
<ul><li><p>
The
CV of <i>EscapeSequence </i><b>::</b>
<i>OctalEscapeSequence</i>
is the CV of the<i> OctalEscapeSequence</i>.</p>
</li>
<li><p>
The
CV of <i>OctalEscapeSequence</i>
<b>::</b>
<i>OctalDigit</i> [<a href="x5.html#lookahead-not-in">lookahead
<span class="symbol">∉</span></a>
<i>DecimalDigit</i>]
is the character whose code unit value is the MV of the
<i>OctalDigit</i>.</p>
</li>
<li><p>
The
CV of <i>OctalEscapeSequence</i>
<b>::</b>
<i>ZeroToThree</i>
<i>OctalDigit</i> [<a href="x5.html#lookahead-not-in">lookahead
<span class="symbol">∉</span></a>
<i>DecimalDigit</i>]
is the character whose code unit value is (8 times the MV of the
<i>ZeroToThree</i>) plus the
MV of the <i>OctalDigit</i>.</p>
</li>
<li><p>
The
CV of <i>OctalEscapeSequence</i>
<b>::</b>
<i>FourToSeven</i>
<i>OctalDigit</i> is the
character whose code unit value is (8 times the MV of the
<i>FourToSeven</i>) plus the
MV of the <i>OctalDigit</i>.</p>
</li>
<li><p>
The
CV of <i>OctalEscapeSequence</i>
<b>::</b>
<i>ZeroToThree</i>
<i>OctalDigit</i> <i>OctalDigit</i>
is the character whose code unit value is (64 (that is, 8<sup>2</sup>)
times the MV of the <i>ZeroToThree</i>)
plus (8 times the MV of the first <i>OctalDigit</i>)
plus the MV of the second <i>OctalDigit</i>.</p>
</li>
<li><p>
The
MV of <i>ZeroToThree</i> <b>::</b>
<code><b>0</b></code>
is 0.</p>
</li>
<li><p>
The
MV of <i>ZeroToThree </i><b>::</b>
<code><b>1</b></code>
is 1.</p>
</li>
<li><p>
The
MV of <i>ZeroToThree </i><b>::</b>
<code><b>2</b></code>
is 2.</p>
</li>
<li><p>
The
MV of <i>ZeroToThree </i><b>::</b>
<code><b>3</b></code>
is 3.</p>
</li>
<li><p>
The
MV of <i>FourToSeven</i> <b>::</b>
<code><b>4</b></code>
is 4.</p>
</li>
<li><p>
The
MV of <i>FourToSeven</i> <b>::</b>
<code><b>5</b></code>
is 5.</p>
</li>
<li><p>
The
MV of <i>FourToSeven</i> <b>::</b>
<code><b>6</b></code>
is 6.</p>
</li>
<li><p>
The
MV of <i>FourToSeven</i> <b>::</b>
<code><b>7</b></code>
is 7.</p>
</li></ul><h3 id="B.2">B.2 Additional Properties <a href="#B.2">#</a> <a href="#B.2-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h3>
<p>
Some
implementations of ECMAScript have included additional properties
for some of the standard native objects. This non-normative annex
suggests uniform semantics for such properties without making the
properties or their semantics part of this standard.</p>
<h4 id="B.2.1">B.2.1 escape (string) <a href="#B.2.1">#</a> <a href="#B.2.1-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h4>
<p>
The
<code><b>escape</b></code> function is
a property of the <a href="x15.1.html#x15.1" class="term-ref">global object</a>. It computes a new version of a
String value in which certain characters have been replaced by a
hexadecimal escape sequence.</p>
<p>
For
those characters being replaced whose code unit value is <code><b>0xFF
</b></code>or less, a two-digit escape sequence of the form <code><b>%</b></code> <i>xx</i>
is used. For those characters being replaced whose code unit value
is greater than <code><b>0xFF</b></code>,
a four-digit escape sequence of the form <code><b>%u</b></code> <i>xxxx</i>
is used</p>
<p>
When
the <code><b>escape</b></code>
function is called with one argument <i>string</i>,
the following steps are taken:</p>
<ol><li><p>
Call
<a href="x9.html#x9.8">ToString</a>(<i>string</i>).</p>
</li>
<li><p>
Compute
the number of characters in Result(1).</p>
</li>
<li><p>
Let
<i>R </i>be the empty string.</p>
</li>
<li><p>
Let
<i>k</i> be 0.</p>
</li>
<li><p>
If
<i>k</i> equals Result(2), return <i>R</i>.</p>
</li>
<li><p>
Get
the character (represented as a 16-bit unsigned integer) at
position <i>k</i> within Result(1).</p>
</li>
<li><p>
If
Result(6) is one of the 69 nonblank
characters<br><code><b>“ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789@*_+-./”<br></b></code>then
go to step 13.</p>
</li>
<li><p>
If
Result(6), is less than 256, go to step 11.</p>
</li>
<li><p>
Let
<i>S</i> be a String containing six characters <code><b>“%u</b></code> <i>wxyz</i><code><b>”</b></code>
where <i>wxyz</i> are four hexadecimal digits encoding the value of
Result(6).</p>
</li>
<li><p>
Go
to step 14.</p>
</li>
<li><p>
Let
<i>S</i> be a String containing three characters <code><b>“%</b></code> <i>xy</i><code><b>”</b></code>
where <i>xy</i> are two hexadecimal digits encoding the value of
Result(6).</p>
</li>
<li><p>
Go
to step 14.</p>
</li>
<li><p>
Let
<i>S</i> be a String containing the single character Result(6).</p>
</li>
<li><p>
Let
<i>R</i> be a new String value computed by concatenating the
previous value of <i>R</i> and <i>S</i>.</p>
</li>
<li><p>
Increase
<i>k</i> by 1.</p>
</li>
<li><p>
Go
to step 5.</p>
</li></ol><p><b class="note">NOTE</b> The
encoding is partly based on the encoding described in RFC 1738, but
the entire encoding specified in this standard is described above
without regard to the contents of RFC 1738. This encoding does not
reflect changes to RFC 1738 made by RFC 3986.</p>
<h4 id="B.2.2">B.2.2 unescape (string) <a href="#B.2.2">#</a> <a href="#B.2.2-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h4>
<p>
The
<code><b>unescape</b></code> function
is a property of the <a href="x15.1.html#x15.1" class="term-ref">global object</a>. It computes a new version of a
String value in which each escape sequence of the sort that might be
introduced by the <code><b>escape</b></code>
function is replaced with the character that it represents.</p>
<p>
When
the <code><b>unescape</b></code>
function is called with one argument <i>string</i>,
the following steps are taken:</p>
<ol><li><p>
Call
<a href="x9.html#x9.8">ToString</a>(<i>string</i>).</p>
</li>
<li><p>
Compute
the number of characters in Result(1).</p>
</li>
<li><p>
Let
<i>R</i> be the empty String.</p>
</li>
<li><p>
Let
<i>k</i> be 0.</p>
</li>
<li><p>
If
<i>k</i> equals Result(2), return <i>R</i>.</p>
</li>
<li><p>
Let
<i>c</i> be the character at position <i>k</i> within Result(1).</p>
</li>
<li><p>
If
<i>c</i> is not <code><b>%</b></code>,
go to step 18.</p>
</li>
<li><p>
If
<i>k</i> is greater than Result(2)<span class="symbol">−</span>6,
go to step 14.</p>
</li>
<li><p>
If
the character at position <i>k</i>+1 within Result(1) is not <code><b>u</b></code>,
go to step 14.</p>
</li>
<li><p>
If
the four characters at positions <i>k</i>+2, <i>k</i>+3, <i>k</i>+4,
and <i>k</i>+5 within Result(1) are not all hexadecimal digits, go
to step 14.</p>
</li>
<li><p>
Let
<i>c</i> be the character whose code unit value is the integer
represented by the four hexadecimal digits at positions <i>k</i>+2,<i>k</i>+3, <i>k</i>+4, and <i>k</i>+5 within Result(1).</p>
</li>
<li><p>
Increase
k by 5.</p>
</li>
<li><p>
Go
to step 18.</p>
</li>
<li><p>
If
<i>k</i> is greater than Result(2)<span class="symbol">−</span>3,
go to step 18.</p>
</li>
<li><p>
If
the two characters at positions <i>k</i>+1 and <i>k</i>+2 within
Result(1) are not both hexadecimal digits, go to step 18.</p>
</li>
<li><p>
Let
<i>c</i> be the character whose code unit value is the integer
represented by two zeroes plus the two hexadecimal digits at
positions <i>k</i>+1 and <i>k</i>+2 within Result(1).</p>
</li>
<li><p>
Increase
<i>k </i>by 2.</p>
</li>
<li><p>
Let
<i>R</i> be a new String value computed by concatenating the
previous value of <i>R</i> and <i>c</i>.</p>
</li>
<li><p>
Increase
<i>k</i> by 1.</p>
</li>
<li><p>
Go
to step 5.</p>
</li></ol><h4 id="B.2.3">B.2.3 String.prototype.substr (start, length) <a href="#B.2.3">#</a> <a href="#B.2.3-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h4>
<p>
The
<code><b>substr</b></code> method
takes two arguments, <i>start</i>
and <i>length</i>, and
returns a substring of the result of converting the this object to a
String, starting from character position <i>start</i>
and running for <i>length</i>
characters (or through the end of the String if <i>length</i>
is <b>undefined</b>). If <i>start</i>
is negative, it is treated as (<i>sourceLength</i>+<i>start</i>)
where <i>sourceLength</i>
is the length of the String. The result is a String value, not a
String object. The following steps are taken:</p>
<ol><li><p>
Call
<a href="x9.html#x9.8">ToString</a>, giving it the <b>this</b> value as its argument.</p>
</li>
<li><p>
Call
<a href="x9.html#x9.4">ToInteger</a>(<i>start</i>).</p>
</li>
<li><p>
If
<i>length</i> is <b>undefined</b>, use <b>+</b><span class="symbol"><b>∞</b></span>;
otherwise call <a href="x9.html#x9.4">ToInteger</a>(<i>length</i>).</p>
</li>
<li><p>
Compute
the number of characters in Result(1).</p>
</li>
<li><p>
If
Result(2) is positive or zero, use Result(2); else use
max(Result(4)+Result(2),0).</p>
</li>
<li><p>
Compute
min(max(Result(3),0), Result(4)–Result(5)).</p>
</li>
<li><p>
If
Result(6) <span class="symbol">≤</span> 0, return the empty
String “”.</p>
</li>
<li><p>
Return
a String containing Result(6) consecutive characters from Result(1)
beginning with the character at position Result(5).</p>
</li></ol><p>
The
<code><b>length</b></code> property of
the <code><b>substr</b></code> method
is <b>2</b>.</p>
<p><b class="note">NOTE</b> The
<code><b>substr</b></code> function is
intentionally generic; it does not require that its <b>this</b>
value be a String object. Therefore it can be transferred to other
kinds of objects for use as a method.</p>
<h4 id="B.2.4">B.2.4 Date.prototype.getYear ( ) <a href="#B.2.4">#</a> <a href="#B.2.4-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h4>
<p><b class="note">NOTE</b> The
<code><b>getFullYear</b></code> method
is preferred for nearly all purposes, because it avoids the “year
2000 problem.”</p>
<p>
When
the <b>getYear</b> method is called with no arguments, the following
steps are taken:</p>
<ol><li><p>
Let
<i>t</i> be <a href="x15.9.html#this-time-value">this time value</a>.</p>
</li>
<li><p>
If
<i>t</i> is <b>NaN</b>, return <b>NaN</b>.</p>
</li>
<li><p>
Return
<a href="x15.9.html#YearFromTime">YearFromTime</a>(<a href="x15.9.html#x15.9.1.9">LocalTime</a>(<i>t</i>)) <span class="symbol">−</span>
1900.</p>
</li></ol><h4 id="B.2.5">B.2.5 Date.prototype.setYear (year) <a href="#B.2.5">#</a> <a href="#B.2.5-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h4>
<p><b class="note">NOTE</b> The
<code><b>setFullYear</b></code> method
is preferred for nearly all purposes, because it avoids the “year
2000 problem.”</p>
<p>
When
the <b>setYear</b> method is called with one argument <i>year</i>,
the following steps are taken:</p>
<ol><li><p>
Let
<i>t</i> be the result of <a href="x15.9.html#x15.9.1.9">LocalTime</a>(<a href="x15.9.html#this-time-value">this time value</a>); but if <a href="x15.9.html#this-time-value">this time value</a> is <b>NaN</b>, let <i>t</i> be <b>+0</b>.</p>
</li>
<li><p>
Call
<a href="x9.html#x9.3">ToNumber</a>(<i>year</i>).</p>
</li>
<li><p>
If
Result(2) is<b> NaN</b>, set the [[PrimitiveValue]] internal
property of the <b>this</b> value to <b>NaN</b> and return <b>NaN</b>.</p>
</li>
<li><p>
If
Result(2) is not <b>NaN</b> and 0 <span class="symbol">≤</span>
<a href="x9.html#x9.4">ToInteger</a>(Result(2)) <span class="symbol">≤</span> 99 then
Result(4) is <a href="x9.html#x9.4">ToInteger</a>(Result(2)) + 1900. Otherwise, Result(4)
is Result(2).</p>
</li>
<li><p>
Compute
<a href="x15.9.html#x15.9.1.12">MakeDay</a>(Result(4), <a href="x15.9.html#x15.9.1.4">MonthFromTime</a>(<i>t</i>), <a href="x15.9.html#x15.9.1.5">DateFromTime</a>(<i>t</i>)).</p>
</li>
<li><p>
Compute
<a href="x15.9.html#x15.9.1.9">UTC</a>(<a href="x15.9.html#x15.9.1.13">MakeDate</a>(Result(5), <a href="x15.9.html#x15.9.1.2">TimeWithinDay</a>(<i>t</i>))).</p>
</li>
<li><p>
Set
the [[PrimitiveValue]] internal property of the <b>this</b> value
to <a href="x15.9.html#x15.9.1.14">TimeClip</a>(Result(6)).</p>
</li>
<li><p>
Return
the value of the [[PrimitiveValue]] internal property of the <b>this</b>
value.</p>
</li></ol><h4 id="B.2.6">B.2.6 Date.prototype.toGMTString ( ) <a href="#B.2.6">#</a> <a href="#B.2.6-toc" class="bak">Ⓣ</a> <b class="erra">Ⓔ</b> <b class="rev1">①</b> <b class="anno">Ⓐ</b></h4>
<p><b class="note">NOTE</b> The
property <code><b>toUTCString</b></code>
is preferred. The <code><b>toGMTString</b></code>
property is provided principally for compatibility with old code. It
is recommended that the <code><b>toUTCString</b></code>
property be used in new ECMAScript code.</p>
<p>
The
Function object that is the initial value of
<code><b>Date.prototype.toGMTString</b></code>
is the same Function object that is the initial value of
<code><b><a href="x15.9.html#x15.9.5.42">Date.prototype.toUTCString</a></b></code>.</p>
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