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126 lines
11 KiB
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<article id="wikiArticle">
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<div> <div class="blockIndicator obsolete obsoleteHeader"><p><strong><span class="icon-only-inline" title="This is an obsolete API and is no longer guaranteed to work."><i class="icon-trash"> </i></span> 已废弃</strong><br/>This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.</p></div></div>
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<p>代理方法<strong><code>handler.enumerate()</code></strong>决定了被代理对象在<a href="Reference/Statements/for...in" title="for...in语句以任意顺序遍历一个对象的可枚举属性。对于每个不同的属性，语句都会被执行。"><code>for...in</code></a>中的行为。不过这个方法已经在ES2016标准中被移除了。</p>
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<h2 id="语法">语法</h2>
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<pre><code class="language-javascript">var p = new Proxy(target, {
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enumerate(target) {
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}
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});
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</code></pre>
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<h3 id="参数">参数</h3>
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<p>下列参数将会被用以调用 <code>enumerate</code> 方法。this将会指向处理器对象。</p>
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<dl>
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<dt><code>target</code></dt>
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<dd>被代理的目标对象。</dd>
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</dl>
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<h3 id="Return_value">Return value</h3>
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<p>该方法应当返回一个<a href="Guide/The_Iterator_protocol">迭代器</a>对象。</p>
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<h2 id="描述">描述</h2>
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<p><code><strong>handler.enumerate</strong></code> 方法决定了被代理对象在<a href="Reference/Statements/for...in" title="for...in语句以任意顺序遍历一个对象的可枚举属性。对于每个不同的属性，语句都会被执行。"><code>for...in</code></a>时的行为。</p>
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<h3 id="触发条件">触发条件</h3>
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<p>这些操作可以触发这个方法。</p>
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<ul>
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<li>for...in: <code>for (var name in proxy) {...}</code></li>
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<li><a href="Reference/Global_Objects/Reflect/enumerate" title="目标对象自身和继承的可迭代属性的一个迭代器。"><code>Reflect.enumerate()</code></a></li>
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</ul>
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<h3 id="Invariants">Invariants</h3>
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<p>If the following invariants are violated, the proxy will throw a <a href="Reference/Global_Objects/TypeError" title="TypeError（类型错误） 对象用来表示值的类型非预期类型时发生的错误。"><code>TypeError</code></a>:</p>
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<ul>
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<li>The <code>enumerate</code> method must return an object.</li>
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</ul>
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<h2 id="Examples">Examples</h2>
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<p>The following code traps <a href="Reference/Statements/for...in" title="for...in语句以任意顺序遍历一个对象的可枚举属性。对于每个不同的属性，语句都会被执行。"><code>for...in</code></a> statements.</p>
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<pre><code class="language-javascript">var p = new Proxy({}, {
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enumerate(target) {
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console.log('called');
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return ['a', 'b', 'c'][Symbol.iterator]();
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}
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});
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for (var x in p) { // "called"
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console.log(x); // "a"
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} // "b"
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// "c"
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</code></pre>
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<p>The following code violates the invariant.</p>
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<pre><code class="language-javascript">var p = new Proxy({}, {
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enumerate(target) {
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return 1;
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}
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});
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for (var x in p) {} // TypeError is thrown
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</code></pre>
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<p>Note: Both examples make use of the shorthand syntax for <a href="/en-US/docs/Web/JavaScript/Reference/Functions/Method_definitions">method definitions</a>.</p>
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<h2 id="Specifications">Specifications</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-proxy-object-internal-methods-and-internal-slots-enumerate" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">[[Enumerate]]</small></a></td>
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<td><span class="spec-Standard">Standard</span></td>
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<td>Initial definition. Removed in ECMAScript 2016.</td>
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</tr>
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</tbody>
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</table>
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<h2 id="Browser_compatibility">Browser compatibility</h2>
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<div>
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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>enumerate</code> <div class="bc-icons"><abbr class="only-icon" title="Deprecated. Not for use in new websites."><span>Deprecated</span><i class="ic-deprecated"></i></abbr><abbr class="only-icon" title="Non-standard. Expect poor cross-browser support."><span>Non-standard</span><i class="ic-non-standard"></i></abbr></div></th><td class="bc-supports-no bc-browser-chrome"><span class="bc-browser-name">Chrome</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-no bc-browser-edge"><span class="bc-browser-name">Edge</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-no bc-browser-firefox"><span class="bc-browser-name">Firefox</span><abbr class="bc-level-no only-icon" title="No support">
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<span>No support</span>
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</abbr>37 — 47</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-no bc-browser-opera"><span class="bc-browser-name">Opera</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-no bc-browser-safari"><span class="bc-browser-name">Safari</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-no bc-browser-webview_android"><span class="bc-browser-name">WebView Android</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-no bc-browser-chrome_android"><span class="bc-browser-name">Chrome Android</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-no bc-browser-edge_mobile"><span class="bc-browser-name">Edge Mobile</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-no bc-browser-firefox_android"><span class="bc-browser-name">Firefox Android</span><abbr class="bc-level-no only-icon" title="No support">
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<span>No support</span>
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</abbr>37 — 47</td><td class="bc-supports-no bc-browser-opera_android"><span class="bc-browser-name">Opera Android</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-no bc-browser-safari_ios"><span class="bc-browser-name">Safari iOS</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-no bc-browser-samsunginternet_android"><span class="bc-browser-name">Samsung Internet Android</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-no bc-browser-nodejs"><span class="bc-browser-name">nodejs</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></tr></tbody></table><section class="bc-legend" id="sect1"><h3 class="offscreen" id="Legend">Legend</h3><dl><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="Non-standard. Expect poor cross-browser support."><span>Non-standard. Expect poor cross-browser support.</span><i class="ic-non-standard"></i></abbr></dt><dd>Non-standard. Expect poor cross-browser support.</dd><dt><abbr class="only-icon" title="Deprecated. Not for use in new websites."><span>Deprecated. Not for use in new websites.</span><i class="ic-deprecated"></i></abbr></dt><dd>Deprecated. Not for use in new websites.</dd></dl></section></div><p></p>
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</div>
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<h2 id="See_also">See also</h2>
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<ul>
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<li><a href="Reference/Global_Objects/Proxy" title="Proxy 对象用于定义基本操作的自定义行为（如属性查找，赋值，枚举，函数调用等）。"><code>Proxy</code></a></li>
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<li><a href="Reference/Global_Objects/Proxy/handler" title="处理器对象用来自定义代理对象的各种可代理操作。"><code>handler</code></a></li>
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<li><a href="Reference/Statements/for...in" title="for...in语句以任意顺序遍历一个对象的可枚举属性。对于每个不同的属性，语句都会被执行。"><code>for...in</code></a> statements</li>
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<li><a href="Reference/Global_Objects/Reflect/enumerate" title="目标对象自身和继承的可迭代属性的一个迭代器。"><code>Reflect.enumerate()</code></a></li>
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</ul>
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</article> |