Revision 988803 of ECMAScript Next support in Mozilla

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

<p>ECMAScript 7 is the next evolution of the ECMA-262 standard (commonly referred to as <a href="/en-US/docs/Web/JavaScript">JavaScript</a>). Even before ECMAScript 6 was finalized on June 17, 2015, new features were already being proposed. You can see the latest proposals on the <a href="https://github.com/tc39/ecma262">tc39/ecma262</a> GitHub repository.</p>

<p>Current issues with the specification process are planned to be solved by introducing <em>stages</em> and <em>champions</em> for feature sets. Also, a two year release cycle for the standard is proposed. For more information about the post-ES6 specification process, see this <a href="https://slides.com/rafaelweinstein/tc39-process">presentation by Rafael Weinstein</a>.</p>

<p>A channel for feedback on ECMAScript standards is <a href="https://mail.mozilla.org/listinfo/es-discuss">es-discuss</a>.</p>

<h2 id="Experimental_features">Experimental features</h2>

<p>The following features are already implemented, but only available in the <a href="https://nightly.mozilla.org/">Firefox Nightly channel</a>:</p>

<h3 id="Additions_to_the_Array_object">Additions to the <code>Array</code> object</h3>

<ul>
 <li>{{jsxref("Array.prototype.includes()")}} (<a href="https://github.com/domenic/Array.prototype.includes/blob/master/spec.md">spec</a>)</li>
</ul>

<h3 id="Additions_to_the_ArrayBuffer_object">Additions to the <code>ArrayBuffer</code> object</h3>

<ul>
 <li>{{jsxref("ArrayBuffer.transfer()")}} (<a href="https://gist.github.com/lukewagner/2735af7eea411e18cf20">spec</a>)</li>
</ul>

<h3 id="New_TypedObject_objects">New TypedObject objects</h3>

<ul>
 <li><a href="https://github.com/dslomov-chromium/typed-objects-es7">Typed Objects draft</a></li>
</ul>

<h3 id="New_SIMD_objects">New SIMD objects</h3>

<ul>
 <li><a href="https://github.com/johnmccutchan/ecmascript_simd">SIMD specification draft and polyfill</a></li>
</ul>

<h2 id="Features_with_ongoing_stabilization">Features with ongoing stabilization</h2>

<p>The following features are supported beyond the Nightly channel, but ongoing specification and implementation work is happening. Features which were originally in the ECMAScript 6 draft and got postponed to ECMAScript 7 are likely to appear here.</p>

<h3 id="Expressions">Expressions</h3>

<ul>
 <li>{{jsxref("Operators/Arithmetic_Operators", "Exponentiation operator", "#Exponentiation", 1)}} (<a href="/en-US/Firefox/Releases/42">Firefox 42</a>)</li>
</ul>

<h2 id="Features_not_yet_supported">Features not yet supported</h2>

<p>The following features are not yet implemented, but targeted for ECMAScript 7.</p>

<ul>
 <li><code>Object.observe()</code> ({{bug(800355)}})</li>
</ul>

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="https://www.ecmascript.org/">ECMAScript web site</a></li>
 <li><a href="https://bugzilla.mozilla.org/show_bug.cgi?id=1021376">Mozilla ES7 tracking bug</a></li>
 <li><a href="https://kangax.github.io/compat-table/es7/">ECMAScript 7 support across browsers</a></li>
</ul>