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author | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
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committer | Peter Bengtsson <mail@peterbe.com> | 2020-12-08 14:40:17 -0500 |
commit | 33058f2b292b3a581333bdfb21b8f671898c5060 (patch) | |
tree | 51c3e392513ec574331b2d3f85c394445ea803c6 /files/zh-cn/web/javascript/reference/global_objects/array/@@iterator | |
parent | 8b66d724f7caf0157093fb09cfec8fbd0c6ad50a (diff) | |
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diff --git a/files/zh-cn/web/javascript/reference/global_objects/array/@@iterator/index.html b/files/zh-cn/web/javascript/reference/global_objects/array/@@iterator/index.html new file mode 100644 index 0000000000..31fe03d8b1 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/array/@@iterator/index.html @@ -0,0 +1,114 @@ +--- +title: 'Array.prototype[@@iterator]()' +slug: Web/JavaScript/Reference/Global_Objects/Array/@@iterator +tags: + - Array + - ECMAScript 2015 + - Iterator + - JavaScript + - Method + - Prototype + - 原型 + - 参考 + - 循环 + - 方法 + - 迭代 +translation_of: Web/JavaScript/Reference/Global_Objects/Array/@@iterator +--- +<div>{{JSRef}}</div> + +<p><code><strong>@@iterator</strong></code> 属性和 {{jsxref("Array.prototype.values()", "Array.prototype.values()")}} 属性的初始值是同一个函数对象。</p> + +<h2 id="语法">语法</h2> + +<pre class="brush: js"><var>arr</var>[Symbol.iterator]()</pre> + +<h3 id="返回值">返回值</h3> + +<p>数组的 <strong>iterator </strong>方法,默认情况下,与 {{jsxref("Array.prototype.values()", "values()")}} 返回值相同, <code>arr[Symbol.iterator]</code> 则会返回 {{jsxref("Array.prototype.values()", "values()")}} 函数。</p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_for...of_循环进行迭代"><font face="Open Sans, Arial, sans-serif">使用 </font><code>for...of</code> 循环进行迭代</h3> + +<pre class="brush: js">var arr = ['a', 'b', 'c', 'd', 'e']; +var eArr = arr[Symbol.iterator](); +// 浏览器必须支持 for...of 循环 +for (let letter of eArr) { + console.log(letter); +} +</pre> + +<h3 id="另一种迭代方式">另一种迭代方式</h3> + +<pre class="brush: js">var arr = ['a', 'b', 'c', 'd', 'e']; +var eArr = arr[Symbol.iterator](); +console.log(eArr.next().value); // a +console.log(eArr.next().value); // b +console.log(eArr.next().value); // c +console.log(eArr.next().value); // d +console.log(eArr.next().value); // e +</pre> + +<h3 id="Use_Case_for_brace_notation">Use Case for brace notation</h3> + +<p>The use case for this syntax over using the dot notation (<code>Array.prototype.values()</code>) is in a case where you don't know what object is going to be ahead of time. If you have a function that takes an iterator and then iterate over the value, but don't know if that Object is going to have a [Iterable].prototype.values method. This could be a built-in object like <a href="/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/String/@@iterator">String</a> object or a custom object.</p> + +<pre class="brush: js">function logIterable(it) { + var iterator = it[Symbol.iterator](); + // 浏览器必须支持 for...of 循环 + for (let letter of iterator) { + console.log(letter); + } +} + +// Array +logIterable(['a', 'b', 'c']); +// a +// b +// c + +// string +logIterable('abc'); +// a +// b +// c</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">规范名称</th> + <th scope="col">规范状态</th> + <th scope="col">备注</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-array.prototype-@@iterator', 'Array.prototype[@@iterator]()')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>首次定义</td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-array.prototype-@@iterator', 'Array.prototype[@@iterator]()')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容性">浏览器兼容性</h2> + + + +<p>{{Compat("javascript.builtins.Array.@@iterator")}}</p> + +<h2 id="参见">参见</h2> + +<ul> + <li>{{jsxref("Array.prototype.keys()")}}</li> + <li>{{jsxref("Array.prototype.entries()")}}</li> + <li>{{jsxref("Array.prototype.forEach()")}}</li> + <li>{{jsxref("Array.prototype.every()")}}</li> + <li>{{jsxref("Array.prototype.some()")}}</li> + <li>{{jsxref("Array.prototype.values()")}}</li> +</ul> |