Revision 652031 of New in JavaScript 1.8.1

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   <p>The following is a changelog for JavaScript 1.8.1. This version was included in <a href="/en-US/Firefox/Releases/3.5">Firefox 3.5</a>.</p>
   <p>JavaScript 1.8.1 is a modest update syntactically to JavaScript; the main change in this release is the addition of the <a href="/en-US/docs/SpiderMonkey/Internals/Tracing_JIT" title="SpiderMonkey/Internals/Tracing JIT">Tracemonkey just-in-time compiler</a>, which improves performance.</p>
   <h2 id="New_features_in_JavaScript_1.5">New features in JavaScript 1.8.1</h2>
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    <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/getPrototypeOf"><code>Object.getPrototypeOf()</code></a></li>
    <li><a href="/en-US/docs/Web/JavaScript/Guide/Using_native_JSON">Support for native JSON</a></li>
    <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/Trim"><code>String.prototype.trim()</code></a></li>
    <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/TrimLeft"><code>String.prototype.trimLeft()</code></a></li>
    <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/TrimRight"><code>String.prototype.trimRight()</code></a></li>
    <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/startsWith"><code>String.prototype.startsWith()</code></a></li>
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   <h2 id="Changed_functionality_in_JavaScript_1.5">Changed functionality in JavaScript 1.8.1</h2>
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 <li>Implicit setting of properties in object and array initializers no longer execute setters in JavaScript. This makes the behavior of setting the values of properties more predictable.</li>
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