Revision 726439 of New in JavaScript 1.2

<div>{{jsSidebar("New_in_JS")}}</div>

<p>The following is a changelog for JavaScript from Netscape Navigator 3.0 to 4.0. The old Netscape documentation can be found on <a href="https://web.archive.org/web/19971015223714/https://developer.netscape.com/library/documentation/communicator/jsguide/js1_2.htm">archive.org</a>. Netscape Navigator 4.0 was released on June 11, 1997. Netscape Navigator 4.0 was the third major version of the browser with JavaScript support.</p>

<h2 id="JavaScript_versions">JavaScript versions</h2>

<p>Netscape Navigator 4.0 executes JavaScript language versions up to 1.2. Note that Netscape Navigator 3.0 and earlier ignored scripts with the language attribute set to "JavaScript1.2" and higher.</p>

<pre class="brush: html">
&lt;SCRIPT LANGUAGE="JavaScript1.1"&gt; &lt;!-- JavaScript for Navigator 3.0. --&gt;
&lt;SCRIPT LANGUAGE="JavaScript1.2"&gt; &lt;!-- JavaScript for Navigator 4.0. --&gt;</pre>

<h2 id="New_features_in_JavaScript_1.2">New features in JavaScript 1.2</h2>

<h3 id="New_objects">New objects</h3>

<ul>
 <li>You can create objects using literal notation (inspired by dictionary literal syntax from Python 1.x).</li>
 <li>Arrays can now be created using literal notation (inspired by list literal syntax from Python 1.x).</li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Functions_and_function_scope/arguments">arguments</a></li>
</ul>

<h3 id="New_properties">New properties</h3>

<ul>
 <li><code><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Function/arity">Function.arity</a></code></li>
</ul>

<h3 id="New_methods">New methods</h3>

<ul>
 <li><code><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat">Array.prototype.concat()</a></code></li>
 <li><code><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/slice">Array.prototype.slice()</a></code></li>
 <li><code><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charCodeAt">String.prototype.charCodeat()</a></code></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/concat"><code>String.prototype.concat()</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/fromCharCode"><code>String.fromCharCode()</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/match"><code>String.prototype.match()</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace"><code>String.prototype.replace()</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/search"><code>String.prototype.search()</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/slice"><code>String.prototype.slice()</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substr"><code>String.prototype.substr()</code></a></li>
</ul>

<h3 id="New_operators">New operators</h3>

<ul>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Operators/delete"><code>delete</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Equality_comparisons_and_when_to_use_them">Equality operators</a> (<code>==</code> and <code>!=</code>)</li>
</ul>

<h3 id="New_statements">New statements</h3>

<ul>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Statements/label">Labeled</a> statements</li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Statements/switch"><code>switch</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Statements/do...while"><code>do...while</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Statements/import"><code>import</code></a></li>
 <li><a href="/en-US/docs/Web/JavaScript/Reference/Statements/export"><code>export</code></a></li>
</ul>

<h3 id="Other_new_features">Other new features</h3>

<ul>
 <li><a href="/en-US/docs/Web/JavaScript/Guide/Regular_Expressions">Regular Expressions</a></li>
 <li><a href="https://web.archive.org/web/19971015223714/https://developer.netscape.com/library/documentation/communicator/jsguide/js1_2.htm">Signed scripts</a></li>
</ul>

<h2 id="Changed_functionality_in_JavaScript_1.2">Changed functionality in JavaScript 1.2</h2>

<ul>
 <li>You can now nest functions within functions.</li>
 <li>Number now converts a specified object to a number.</li>
 <li>Number now produces <code>NaN</code> rather than an error if <code>x</code> is a string that does not contain a well-formed numeric literal.</li>
 <li>String now converts a specified object to a string.</li>
 <li><code><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort">Array.prototype.sort()</a></code> now works on all platforms. It no longer converts undefined elements to null and sorts them to the high end of the array.</li>
 <li><code><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split">String.prototype.split()</a></code>
  <ul>
   <li>It can take a regular expression argument, as well as a fixed string, by which to split the object string.</li>
   <li>It can take a limit count so that it won't include trailing empty elements in the resulting array.</li>
  </ul>
 </li>
 <li><code><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/substring">String.prototype.substring()</a></code>: no longer swaps index numbers when the first index is greater than the second.</li>
 <li><code>toString()</code>: now converts the object or array to a literal.</li>
 <li>The <a href="/en-US/docs/Web/JavaScript/Reference/Statements/break"><code>break</code></a> and <a href="/en-US/docs/Web/JavaScript/Reference/Statements/continue"><code>continue</code></a> statements can now be used with the new labeled statement.</li>
</ul>