Revision 52781 of New in JavaScript 1.8.5

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<p>JavaScript 1.8.5 is the version of JavaScript included in Firefox 4.</p>
<h2 id="New_functions">New functions</h2>
<table class="standard-table"> <thead> <tr> <th scope="col">Function</th> <th scope="col">Description</th> </tr> </thead> <tbody> <tr> <td><code><a class="internal" href="/en/JavaScript/Reference/Global_Objects/Object/create" title="En/Core JavaScript 1.5
            Reference/Global Objects/Object/Create">Object.create</a></code></td> <td>Creates a new object with the specified prototype object and properties. {{ bug("492840") }}</td> </tr> <tr> <td><code><a class="internal" href="/en/JavaScript/Reference/Global_Objects/Object/defineProperty" title="En/Core JavaScript 1.5 Reference/Global
            Objects/Object/DefineProperty">Object.defineProperty</a></code></td> <td>Adds the named property described by a given descriptor to an object.</td> </tr> <tr> <td><code><a class="internal" href="/en/JavaScript/Reference/Global_Objects/Object/defineProperties" title="En/Core JavaScript 1.5 Reference/Global
            Objects/Object/DefineProperties">Object.defineProperties</a></code></td> <td>Adds the named properties described by the given descriptors to an object.</td> </tr> <tr> <td><code><a class="internal" href="/en/JavaScript/Reference/Global_Objects/Object/getOwnPropertyDescriptor" title="En/Core JavaScript 1.5 Reference/Global
            Objects/Object/GetOwnPropertyDescriptor">Object.getOwnPropertyDescriptor</a></code></td> <td>Returns a property descriptor for a named property on an object. {{ bug("505587") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Object/keys" title="en/Core JavaScript
            1.5 Reference/Global Objects/Object/keys"><code>Object.keys</code></a></td> <td>Returns an array of all enumerable properties on an object. {{ bug("307791") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames" title="en/Core
            JavaScript 1.5 Reference/Global Objects/Object/getOwnPropertyNames"><code>Object.getOwnPropertyNames </code></a></td> <td>Returns an array of all enumerable and non-enumerable properties on an object. {{ bug("518663") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Object/preventExtensions" title="en/Core
            JavaScript 1.5 Reference/Global Objects/Object/preventExtensions"><code>Object.preventExtensions</code></a></td> <td>Prevents any extensions of an object. {{ bug("492849") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Object/isExtensible" title="en/Core
            JavaScript 1.5 Reference/Global Objects/Object/isExtensible"><code>Object.isExtensible</code></a></td> <td>Determine if extending of an object is allowed. {{ bug("492849") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Object/seal" title="en/Core
            JavaScript 1.5 Reference/Global Objects/Object/seal"><code>Object.seal</code></a></td> <td>Prevents other code from deleting properties of an object. {{ bug("492845") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Object/isSealed" title="en/Core
            JavaScript 1.5 Reference/Global Objects/Object/isSealed"><code>Object.isSealed</code></a></td> <td>Determine if an object is sealed. {{ bug("492845") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Object/freeze" title="en/Core
            JavaScript 1.5 Reference/Global Objects/Object/freezed"><code>Object.freeze</code></a></td> <td>Freezes an object: other code can't delete or change any properties. {{ bug("492844") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Object/isFrozen" title="en/Core
            JavaScript 1.5 Reference/Global Objects/Object/isFrozen"><code>Object.isFrozen</code></a></td> <td>Determine if an object was frozen. {{ bug("492844") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Array/isArray" title="en/Core JavaScript
            1.5 Reference/Global Objects/Array/isArray"><code>Array.isArray </code></a></td> <td>Checks if a variable is an array. {{ bug("510537") }}</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Date/toJSON" title="en/JavaScript/Reference/Global Objects/Date/toJSON"><code>Date.toJSON</code></a></td> <td>Returns a JSON format string for a <code>Date</code> object.</td> </tr> <tr> <td><a href="/en/JavaScript/Reference/Global_Objects/Function/bind" title="en/JavaScript/Reference/Global_Objects/Function/bind"><code>Function.prototype.bind</code></a></td> <td>Creates a new function that, when called, itself calls this function in the context provided (with a given sequence of arguments) {{ bug("429507") }}</td> </tr> </tbody>
</table>
<h2 id="New_ECMAScript5_features">New ECMAScript5 features</h2>
<ul> <li><code><a href="/en/JavaScript/Reference/Operators/get" title="en/JavaScript/Reference/Operators/Special Operators/get Operator">get</a></code> and <code><a href="/en/JavaScript/Reference/Operators/set" title="en/JavaScript/Reference/Operators/Special Operators/set Operator">set</a></code> operators now allows the identifier to be numeric or a string. {{ bug("520696") }}</li> <li><a href="/en/JavaScript/Reference/Global_Objects/Function/apply" title="en/JavaScript/Reference/Global Objects/Function/apply"><code>Function.apply()</code></a> can accept any array-like object as the arguments list, instead of only true arrays.</li> <li><a href="/en/JavaScript/Reference/Functions_and_function_scope/Strict_mode" title="en/JavaScript/Strict mode">strict mode support</a></li> <li><a href="/en/JavaScript/Reference/Global_Objects/Array/toString" title="en/JavaScript/Reference/Global Objects/Array/toString"><code>Array.toString()</code></a> now works even on non-arrays by either returning the result of calling its <a href="/en/JavaScript/Reference/Global_Objects/Array/join" title="en/JavaScript/Reference/Global Objects/Array/join"><code>join()</code></a> method if one is available or by calling its <a href="/en/JavaScript/Reference/Global_Objects/Object/toString" title="en/JavaScript/Reference/Global Objects/Object/toString"><code>toString()</code></a> method.</li>
</ul>
<h2 id="Other_standardization_work">Other standardization work</h2>
<p>Various non-standard syntaxes for defining getters and setters have been removed; ECMAScript 5 defined syntax has not been changed. These were all pretty esoteric and rarely used; if this affects you, see <a class="external" href="https://whereswalden.com/2010/04/16/more-spidermonkey-changes-ancient-esoteric-very-rarely-used-syntax-for-creating-getters-and-setters-is-being-removed/" title="https://whereswalden.com/2010/04/16/more-spidermonkey-changes-ancient-esoteric-very-rarely-used-syntax-for-creating-getters-and-setters-is-being-removed/">this blog post</a> for details.</p>
<h2 id="New_objects">New objects</h2>
<table class="standard-table"> <thead> <tr> <th scope="col">Object</th> <th scope="col">Description</th> </tr> </thead> <tbody> <tr> <td><code><a href="/en/JavaScript/Reference/Global_Objects/Proxy" title="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Proxy">Proxy</a></code></td> <td>Offers support for creating <code>Object</code> and <code>Function</code> proxies that enable meta-programming in JavaScript.</td> </tr> </tbody>
</table>
<h2 id="Changes_to_global_objects">Changes to global objects</h2>
<dl> <dt>ISO 8601 support in <code>Date</code></dt> <dd>The <a href="/en/JavaScript/Reference/Global_Objects/Date" title="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date"><code>Date</code></a> object's <a href="/en/JavaScript/Reference/Global_Objects/Date/parse" title="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/parse"><code>parse()</code></a> method now supports simple ISO 8601 format date strings.</dd> <dt>Global objects made read only</dt> <dd>The <a href="/en/JavaScript/Reference/Global_Objects/NaN" title="en/JavaScript/Reference/Global Objects/NaN"><code>NaN</code></a>, <a href="/en/JavaScript/Reference/Global_Objects/Infinity" title="en/JavaScript/Reference/Global Objects/Infinity"><code>Infinity</code></a>, and <a href="/en/JavaScript/Reference/Global_Objects/undefined" title="en/JavaScript/Reference/Global Objects/undefined"><code>undefined</code></a> global objects have been made read only, per the ECMAScript 5 specification.</dd>
</dl>
<h2 id="Additional_changes">Additional changes</h2>
<ul> <li><a href="/en/JavaScript/Reference/Global_Objects/Object/Parent" title="en/JavaScript/Reference/Global Objects/Object/Parent"><code>obj.__parent__</code></a> and <code>obj.__count__</code> become obsolete. Some information about why: <a class="external" href="https://whereswalden.com/2010/05/07/spidermonkey-change-du-jour-the-special-__parent__-property-has-been-removed/" title="https://whereswalden.com/2010/05/07/spidermonkey-change-du-jour-the-special-__parent__-property-has-been-removed/">SpiderMonkey change du jour: the special __parent__ property has been removed</a> {{ bug("551529") }} &amp; {{ bug("552560") }}.</li> <li>Trailing commas no longer accepted in <a href="/En/Using_native_JSON" title="En/Using native JSON"><code>JSON.parse()</code></a>.</li>
</ul>
<h2 id="JavaScript_(SpiderMonkey)_API changes">JavaScript (SpiderMonkey) API changes</h2>
<div class="note"><strong>Note:</strong> Locale callbacks (as specified in the <a href="/en/JSLocaleCallbacks" title="en/JSLocaleCallbacks">JSLocaleCallbacks</a> structure) should not free the memory buffer passed to them; this buffer is managed by the SpiderMonkey runtime.</div>
<p>The <a href="/en/SpiderMonkey/JSAPI_Reference/JS_NewString" title="en/SpiderMonkey/JSAPI Reference/JS NewString"><code>JS_NewString()</code></a> function was removed in SpiderMonkey 1.8.5. Use <a href="/en/SpiderMonkey/JSAPI_Reference/JS_NewStringCopyN" title="en/SpiderMonkey/JSAPI Reference/JS NewStringCopyN"><code>JS_NewStringCopyN()</code></a> instead.</p>
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