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136 lines
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<article id="wikiArticle">
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<div></div>
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<p><code><strong>@@iterator</strong></code><strong> </strong>属性的初始值与 <a href="Reference/Global_Objects/Map/entries" title="entries() ?方法返回一个新的包含 [key, value] ?对的 Iterator ?对象，返回的迭代器的迭代顺序与 Map 对象的插入顺序相同。"><code>entries</code></a> 属性的初始值是同一个函数对象。</p>
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<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/map-prototype-@@iterator.html" width="100%"></iframe></div>
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<p class="hidden">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>
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<h2 id="语法">语法</h2>
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<pre><code class="language-javascript"><code><em>myMap</em>[Symbol.iterator]</code></code></pre>
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<h3 id="返回值">返回值</h3>
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<p>map 的 <strong>iterator</strong> 函数默认就是 <a href="Reference/Global_Objects/Map/entries" title="entries() ?方法返回一个新的包含 [key, value] ?对的 Iterator ?对象，返回的迭代器的迭代顺序与 Map 对象的插入顺序相同。"><code>entries()</code></a> 函数。</p>
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<h2 id="示例">示例</h2>
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<h3 id="使用_iterator()">使用 <code>[@@iterator]()</code></h3>
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<pre><code class="language-js">var myMap = new Map();
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myMap.set('0', 'foo');
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myMap.set(1, 'bar');
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myMap.set({}, 'baz');
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var mapIter = myMap[Symbol.iterator]();
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//返回的其实是个generator
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console.log(mapIter.next().value); // ["0", "foo"]
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console.log(mapIter.next().value); // [1, "bar"]
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console.log(mapIter.next().value); // [Object, "baz"]
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</code></pre>
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<h3 id="在for..of中使用iterator()">在<code>for..of中</code>使用<code>[@@iterator]()</code> </h3>
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<pre><code class="language-js">var myMap = new Map();
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myMap.set('0', 'foo');
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myMap.set(1, 'bar');
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myMap.set({}, 'baz');
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for (const entry of myMap) {
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console.log(entry);
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}
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// ["0", "foo"]
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// [1, "bar"]
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// [{}, "baz"]
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for (var v of myMap) {
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console.log(v);
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}
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// 0: foo
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// 1: bar
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// [Object]: baz</code></pre>
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<h2 id="规范">规范</h2>
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<table class="standard-table">
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<tbody>
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<tr>
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<th scope="col">Specification</th>
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<th scope="col">Status</th>
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<th scope="col">Comment</th>
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</tr>
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<tr>
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<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#sec-map.prototype-@@iterator" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Map.prototype[@@iterator]()</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td>Initial definition.</td>
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</tr>
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<tr>
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<td><a class="external" href="https://tc39.github.io/ecma262/#sec-map.prototype-@@iterator" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">Map.prototype[@@iterator]()</small></a></td>
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<td><span class="spec-Draft">Draft</span></td>
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<td> </td>
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</tr>
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</tbody>
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</table>
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<h2 id="浏览器兼容">浏览器兼容</h2>
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<div class="hidden">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.</div>
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<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>@@iterator</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">
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<span>Full support</span>
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</abbr>
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Yes</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">
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<span>Full support</span>
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</abbr>
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Yes</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">
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<span>Full support</span>
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</abbr>
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36<div class="bc-icons"></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">
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<span>Full support</span>
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</abbr>
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36<div class="bc-icons"></div></dt><dd></dd><dt class="bc-supports-no bc-supports"><abbr class="bc-level-no only-icon" title="No support">
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<span>No support</span>
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</abbr>27 — 36<div class="bc-icons"><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> <abbr class="only-icon" title="Uses the non-standard name: <code>@@iterator</code>"><span>Alternate Name</span><i class="ic-altname"></i></abbr> </div></dt><dd><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> A placeholder property named <code>@@iterator</code> is used.</dd><dd><abbr class="only-icon" title="Uses the non-standard name: <code>@@iterator</code>"><span>Alternate Name</span><i class="ic-altname"></i></abbr> Uses the non-standard name: <code>@@iterator</code></dd><dt class="bc-supports-no bc-supports"><abbr class="bc-level-no only-icon" title="No support">
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<span>No support</span>
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</abbr>17 — 27<div class="bc-icons"><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> <abbr class="only-icon" title="Uses the non-standard name: <code>iterator</code>"><span>Alternate Name</span><i class="ic-altname"></i></abbr> </div></dt><dd><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> A placeholder property named <code>iterator</code> is used.</dd><dd><abbr class="only-icon" title="Uses the non-standard name: <code>iterator</code>"><span>Alternate Name</span><i class="ic-altname"></i></abbr> Uses the non-standard name: <code>iterator</code></dd></dl></section></td><td class="bc-supports-no bc-browser-ie"><span class="bc-browser-name">IE</span><abbr class="bc-level-no only-icon" title="No support">
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<span>No support</span>
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</abbr>
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No</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">
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<span>Full support</span>
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</abbr>
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Yes</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">
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<span>Full support</span>
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</abbr>
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Yes</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">
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<span>Full support</span>
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</abbr>
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Yes</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">
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<span>Full support</span>
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</abbr>
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Yes</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">
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<span>Full support</span>
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</abbr>
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Yes</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">
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<span>Full support</span>
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</abbr>
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36<div class="bc-icons"></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">
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<span>Full support</span>
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</abbr>
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36<div class="bc-icons"></div></dt><dd></dd><dt class="bc-supports-no bc-supports"><abbr class="bc-level-no only-icon" title="No support">
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<span>No support</span>
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</abbr>27 — 36<div class="bc-icons"><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> <abbr class="only-icon" title="Uses the non-standard name: <code>@@iterator</code>"><span>Alternate Name</span><i class="ic-altname"></i></abbr> </div></dt><dd><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> A placeholder property named <code>@@iterator</code> is used.</dd><dd><abbr class="only-icon" title="Uses the non-standard name: <code>@@iterator</code>"><span>Alternate Name</span><i class="ic-altname"></i></abbr> Uses the non-standard name: <code>@@iterator</code></dd><dt class="bc-supports-no bc-supports"><abbr class="bc-level-no only-icon" title="No support">
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<span>No support</span>
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</abbr>17 — 27<div class="bc-icons"><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> <abbr class="only-icon" title="Uses the non-standard name: <code>iterator</code>"><span>Alternate Name</span><i class="ic-altname"></i></abbr> </div></dt><dd><abbr class="only-icon" title="See implementation notes"><span>Notes</span><i class="ic-footnote"></i></abbr> A placeholder property named <code>iterator</code> is used.</dd><dd><abbr class="only-icon" title="Uses the non-standard name: <code>iterator</code>"><span>Alternate Name</span><i class="ic-altname"></i></abbr> Uses the non-standard name: <code>iterator</code></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">
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<span>Full support</span>
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</abbr>
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Yes</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">
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<span>Full support</span>
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</abbr>
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Yes</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">
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<span>Full support</span>
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</abbr>
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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">
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<span>Full support</span>
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</abbr>
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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">
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<abbr class="bc-level bc-level-yes only-icon" title="Full support">
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<span>Full support</span>
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</abbr></span></dt><dd>Full support</dd><dt><span class="bc-supports-no bc-supports">
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<abbr class="bc-level bc-level-no only-icon" title="No support">
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<span>No support</span>
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</abbr></span></dt><dd>No 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><dt><abbr class="only-icon" title="Uses a non-standard name."><span>Uses a non-standard name.</span><i class="ic-altname"></i></abbr></dt><dd>Uses a non-standard name.</dd></dl></section></div><p></p>
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<h2 id="另见">另见</h2>
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<ul>
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<li><a href="Reference/Global_Objects/Map/entries" title="entries() ?方法返回一个新的包含 [key, value] ?对的 Iterator ?对象，返回的迭代器的迭代顺序与 Map 对象的插入顺序相同。"><code>Map.prototype.entries()</code></a></li>
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<li><a href="Reference/Global_Objects/Map/keys" title="keys() 返回一个新的 Iterator 对象。它包含按照顺序插入 Map 对象中每个元素的key值。"><code>Map.prototype.keys()</code></a></li>
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<li><a href="Reference/Global_Objects/Map/values" title="一个新的 Map 可迭代对象."><code>Map.prototype.values()</code></a></li>
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</ul>
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</article> |