2019-04-21 11:50:48 +08:00

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<article id="wikiArticle">
<div></div>
<p><strong>Size</strong>属性将会返回<a href="Reference/Global_Objects/Set" title="Set 对象允许你存储任何类型的唯一值无论是原始值或者是对象引用。"><code>Set</code></a>对象中元素的个数。</p>
<p><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/set-prototype-size.html" width="100%"></iframe></p>
<div class="hidden">
<p>The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone <a class="external" href="https://github.com/mdn/interactive-examples" rel="noopener">https://github.com/mdn/interactive-examples</a> and send us a pull request.</p>
</div>
<h2 id="描述">描述</h2>
<p><code>size</code>的值是一个整数,表示<code>Set</code>对象有多少条目。<code>size</code>的集合访问函数是<code>undefined</code>; 你不能改变这个属性。</p>
<h2 id="例子">例子</h2>
<h3 id="使用size">使用<code>size</code></h3>
<pre><code class="language-js">var mySet = new Set();
mySet.add(1);
mySet.add(5);
mySet.add("some text")
mySet.size; // 3
</code></pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
<tr>
<td>
<p><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-get-set.prototype.size" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Set.prototype.size</small></a></p>
</td>
<td><span class="spec-Standard">Standard</span></td>
<td>初始定义</td>
</tr>
<tr>
<td>
<p><a class="external" href="https://tc39.github.io/ecma262/#sec-get-set.prototype.size" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">Set.prototype.size</small></a></p>
</td>
<td><span class="spec-Draft">Draft</span></td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容">浏览器兼容</h2>
<div class="hidden">
<p>The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out <a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</p>
</div>
<p></p><div class="bc-data"><a class="bc-github-link external" href="https://github.com/mdn/browser-compat-data" rel="noopener">Update compatibility data on GitHub</a><table class="bc-table bc-table-js"><thead><tr class="bc-platforms"><td></td><th class="bc-platform-desktop" colspan="6"><span>Desktop</span></th><th class="bc-platform-mobile" colspan="7"><span>Mobile</span></th><th class="bc-platform-server" colspan="1"><span>Server</span></th></tr><tr class="bc-browsers"><td></td><th class="bc-browser-chrome"><span class="bc-head-txt-label bc-head-icon-chrome">Chrome</span></th><th class="bc-browser-edge"><span class="bc-head-txt-label bc-head-icon-edge">Edge</span></th><th class="bc-browser-firefox"><span class="bc-head-txt-label bc-head-icon-firefox">Firefox</span></th><th class="bc-browser-ie"><span class="bc-head-txt-label bc-head-icon-ie">Internet Explorer</span></th><th class="bc-browser-opera"><span class="bc-head-txt-label bc-head-icon-opera">Opera</span></th><th class="bc-browser-safari"><span class="bc-head-txt-label bc-head-icon-safari">Safari</span></th><th class="bc-browser-webview_android"><span class="bc-head-txt-label bc-head-icon-webview_android">Android webview</span></th><th class="bc-browser-chrome_android"><span class="bc-head-txt-label bc-head-icon-chrome_android">Chrome for Android</span></th><th class="bc-browser-edge_mobile"><span class="bc-head-txt-label bc-head-icon-edge_mobile">Edge Mobile</span></th><th class="bc-browser-firefox_android"><span class="bc-head-txt-label bc-head-icon-firefox_android">Firefox for Android</span></th><th class="bc-browser-opera_android"><span class="bc-head-txt-label bc-head-icon-opera_android">Opera for Android</span></th><th class="bc-browser-safari_ios"><span class="bc-head-txt-label bc-head-icon-safari_ios">Safari on iOS</span></th><th class="bc-browser-samsunginternet_android"><span class="bc-head-txt-label bc-head-icon-samsunginternet_android">Samsung Internet</span></th><th class="bc-browser-nodejs"><span class="bc-head-txt-label bc-head-icon-nodejs">Node.js</span></th></tr></thead><tbody><tr><th scope="row"><code>size</code></th><td class="bc-supports-yes bc-browser-chrome"><span class="bc-browser-name">Chrome</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
38</td><td class="bc-supports-yes bc-browser-edge"><span class="bc-browser-name">Edge</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
12</td><td class="bc-supports-yes bc-browser-firefox bc-has-history"><span class="bc-browser-name">Firefox</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
19<div class="bc-icons"><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> </div><section class="bc-history" id="sect1"><dl><dt class="bc-supports-yes bc-supports"><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
19<div class="bc-icons"><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> </div></dt><dd><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> From Firefox 13 to Firefox 18, the <code>size</code> property was implemented as a <code>Set.prototype.size()</code> method, this has been changed to a property in later versions conform to the ECMAScript 2015 specification.</dd></dl></section></td><td class="bc-supports-yes bc-browser-ie"><span class="bc-browser-name">IE</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
11</td><td class="bc-supports-yes bc-browser-opera"><span class="bc-browser-name">Opera</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
25</td><td class="bc-supports-yes bc-browser-safari"><span class="bc-browser-name">Safari</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
8</td><td class="bc-supports-yes bc-browser-webview_android"><span class="bc-browser-name">WebView Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
38</td><td class="bc-supports-yes bc-browser-chrome_android"><span class="bc-browser-name">Chrome Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
38</td><td class="bc-supports-yes bc-browser-edge_mobile"><span class="bc-browser-name">Edge Mobile</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
12</td><td class="bc-supports-yes bc-browser-firefox_android bc-has-history"><span class="bc-browser-name">Firefox Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
19<div class="bc-icons"><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> </div><section class="bc-history" id="sect2"><dl><dt class="bc-supports-yes bc-supports"><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
19<div class="bc-icons"><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> </div></dt><dd><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> From Firefox 13 to Firefox 18, the <code>size</code> property was implemented as a <code>Set.prototype.size()</code> method, this has been changed to a property in later versions conform to the ECMAScript 2015 specification.</dd></dl></section></td><td class="bc-supports-yes bc-browser-opera_android"><span class="bc-browser-name">Opera Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
25</td><td class="bc-supports-yes bc-browser-safari_ios"><span class="bc-browser-name">Safari iOS</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
8</td><td class="bc-supports-yes bc-browser-samsunginternet_android"><span class="bc-browser-name">Samsung Internet Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
Yes</td><td class="bc-supports-yes bc-browser-nodejs"><span class="bc-browser-name">nodejs</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
0.12</td></tr></tbody></table><section class="bc-legend" id="sect3"><h3 class="offscreen" id="Legend">Legend</h3><dl><dt><span class="bc-supports-yes bc-supports">
<abbr class="bc-level bc-level-yes only-icon" title="Full support">
<span>Full support</span>
 
</abbr></span></dt><dd>Full support</dd><dt><abbr class="only-icon" title="See implementation notes."><span>See implementation notes.</span><i class="ic-footnote"></i></abbr></dt><dd>See implementation notes.</dd></dl></section></div><p></p>
<h2 id="参见">参见</h2>
<ul>
<li><a href="Reference/Global_Objects/Set" title="Set 对象允许你存储任何类型的唯一值无论是原始值或者是对象引用。"><code>Set</code></a></li>
</ul>
</article>