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101 lines
3.7 KiB
HTML
101 lines
3.7 KiB
HTML
<article id="wikiArticle">
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<div></div>
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<h2 id="Summary" name="Summary">概述</h2>
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<p><code><strong>Symbol.keyFor(sym)</strong></code> 方法用来获取 symbol 注册表中与某个 symbol 关联的键。</p>
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<h2 id="Syntax" name="Syntax">语法</h2>
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<pre><code class="language-javascript"><var>Symbol.keyFor(sym)</var>;</code></pre>
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<h3 id="参数">参数</h3>
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<dl>
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<dt>sym</dt>
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<dd>存储在 symbol 注册表中的某个 symbol</dd>
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</dl>
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<h2 id="示例">示例</h2>
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<pre><code class="language-javascript">// 创建一个 symbol 并放入 Symbol 注册表，key 为 "foo"
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var globalSym = Symbol.for("foo");
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Symbol.keyFor(globalSym); // "foo"
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// 创建一个 symbol，但不放入 symbol 注册表中
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var localSym = Symbol();
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Symbol.keyFor(localSym); // undefined，所以是找不到 key 的
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// well-known symbol 们并不在 symbol 注册表中
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Symbol.keyFor(Symbol.iterator) // undefined
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</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-symbol.keyfor" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">Symbol.keyFor</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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</tbody>
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</table>
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<h2 id="浏览器兼容性">浏览器兼容性</h2>
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<p></p><div class="blockIndicator warning"><strong><a class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">We're converting our compatibility data into a machine-readable JSON format</a></strong>.
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This compatibility table still uses the old format,
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because we haven't yet converted the data it contains.
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<strong><a class="new" href="/zh-CN/docs/MDN/Contribute/Structures/Compatibility_tables" rel="nofollow">Find out how you can help!</a></strong></div>
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<div class="htab">
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<a id="AutoCompatibilityTable" name="AutoCompatibilityTable"></a>
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<ul>
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<li class="selected"><a>Desktop</a></li>
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<li><a>Mobile</a></li>
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</ul>
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</div><p></p>
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<div id="compat-desktop">
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<table class="compat-table">
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<tbody>
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<tr>
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<th>Feature</th>
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<th>Chrome</th>
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<th>Firefox (Gecko)</th>
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<th>Internet Explorer</th>
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<th>Opera</th>
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<th>Safari</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><a href="/en-US/Firefox/Releases/33" title="Released on 2014-10-14.">33.0</a> (33.0)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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</tbody>
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</table>
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</div>
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<div id="compat-mobile">
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<table class="compat-table">
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<tbody>
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<tr>
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<th>Feature</th>
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<th>Android</th>
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<th>Chrome for Android</th>
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<th>Firefox Mobile (Gecko)</th>
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<th>IE Mobile</th>
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<th>Opera Mobile</th>
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<th>Safari Mobile</th>
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</tr>
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<tr>
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<td>Basic support</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td>33.0 (33.0)</td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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<td><span style="color: #f00;">未实现</span></td>
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</tr>
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</tbody>
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</table>
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</div>
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<h2 id="See_Also" name="See_Also">相关链接</h2>
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<ul>
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<li><a href="Reference/Global_Objects/Symbol/for" title="Symbol.for(key) 方法会根据给定的键 key，来从运行时的 symbol 注册表中找到对应的 symbol，如果找到了，则返回它，否则，新建一个与该键关联的 symbol，并放入全局 symbol 注册表中。"><code>Symbol.prototype.for()</code></a></li>
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</ul>
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</article> |