From 33058f2b292b3a581333bdfb21b8f671898c5060 Mon Sep 17 00:00:00 2001
From: Peter Bengtsson <mail@peterbe.com>
Date: Tue, 8 Dec 2020 14:40:17 -0500
Subject: initial commit

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+---
+title: Object.fromEntries()
+slug: Web/JavaScript/Reference/Global_Objects/Object/fromEntries
+translation_of: Web/JavaScript/Reference/Global_Objects/Object/fromEntries
+---
+<div>{{JSRef}}</div>
+
+<p> <code><strong>Object.fromEntries()</strong></code> 方法把键值对列表转换为一个对象。</p>
+
+<div>{{EmbedInteractiveExample("pages/js/object-fromentries.html")}}</div>
+
+
+
+<h2 id="语法">语法</h2>
+
+<pre class="syntaxbox notranslate">Object.fromEntries(<var>iterable</var>);</pre>
+
+<h3 id="参数">参数</h3>
+
+<dl>
+ <dt><code>iterable</code></dt>
+ <dd>类似 {{jsxref("Array")}} 、 {{jsxref("Map")}} 或者其它实现了<a href="/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#The_iterable_protocol">可迭代协议</a>的可迭代对象。</dd>
+</dl>
+
+<h3 id="返回值">返回值</h3>
+
+<p>一个由该迭代对象条目提供对应属性的新对象。</p>
+
+<h2 id="描述">描述</h2>
+
+<p><code>Object.fromEntries()</code> 方法接收一个键值对的列表参数，并返回一个带有这些键值对的新对象。这个迭代参数应该是一个能够实现<code>@@iterator</code>方法的的对象，返回一个迭代器对象。它生成一个具有两个元素的类数组的对象，第一个元素是将用作属性键的值，第二个元素是与该属性键关联的值。</p>
+
+<p><code>Object.fromEntries()</code> 执行与 {{jsxref("Object.entries")}} 互逆的操作。</p>
+
+<h2 id="示例">示例</h2>
+
+<h3 id="Map_转化为_Object"> <code>Map</code> 转化为 <code>Object</code></h3>
+
+<p>通过 <code>Object.fromEntries</code>， 可以将 {{jsxref("Map")}} 转换为 {{jsxref("Object")}}:</p>
+
+<pre class="brush: js notranslate">const map = new Map([ ['foo', 'bar'], ['baz', 42] ]);
+const obj = Object.fromEntries(map);
+console.log(obj); // { foo: "bar", baz: 42 }
+</pre>
+
+<h3 id="Array_转化为_Object"><code>Array</code> 转化为 <code>Object</code></h3>
+
+<p>通过 <code>Object.fromEntries</code>， 可以将 {{jsxref("Array")}} 转换为 {{jsxref("Object")}}:</p>
+
+<pre class="brush: js notranslate">const arr = [ ['0', 'a'], ['1', 'b'], ['2', 'c'] ];
+const obj = Object.fromEntries(arr);
+console.log(obj); // { 0: "a", 1: "b", 2: "c" }
+</pre>
+
+<h3 id="对象转换">对象转换</h3>
+
+<p><code>Object.fromEntries</code> 是与 {{jsxref("Object.entries()")}} 相反的方法，用 <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array#Methods_2">数组处理函数</a> 可以像下面这样转换对象：</p>
+
+<pre class="brush: js notranslate">const object1 = { a: 1, b: 2, c: 3 };
+
+const object2 = Object.fromEntries(
+  Object.entries(object1)
+  .map(([ key, val ]) =&gt; [ key, val * 2 ])
+);
+
+console.log(object2);
+// { a: 2, b: 4, c: 6 }</pre>
+
+<h2 id="规范">规范</h2>
+
+<table class="standard-table">
+ <thead>
+  <tr>
+   <th scope="col">规范</th>
+   <th scope="col">状态</th>
+   <th scope="col">备注</th>
+  </tr>
+ </thead>
+ <tbody>
+  <tr>
+   <td>{{SpecName('ESDraft', '#sec-object.fromentries', 'Object.fromEntries')}}</td>
+   <td>{{Spec2('ESDraft')}}</td>
+   <td>在 ECMAScript 2019 中首次被定义。</td>
+  </tr>
+ </tbody>
+</table>
+
+<h2 id="浏览器兼容">浏览器兼容</h2>
+
+<div>
+
+
+<p>{{Compat("javascript.builtins.Object.fromEntries")}}</p>
+</div>
+
+<h2 id="相关链接">相关链接</h2>
+
+<ul>
+ <li>{{jsxref("Object.entries()")}}</li>
+ <li>{{jsxref("Object.keys()")}}</li>
+ <li>{{jsxref("Object.values()")}}</li>
+ <li>{{jsxref("Map.prototype.entries()")}}</li>
+ <li>{{jsxref("Map.prototype.keys()")}}</li>
+ <li>{{jsxref("Map.prototype.values()")}}</li>
+</ul>
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