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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/symbol/species/index.html | |
parent | 8b66d724f7caf0157093fb09cfec8fbd0c6ad50a (diff) | |
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diff --git a/files/zh-cn/web/javascript/reference/global_objects/symbol/species/index.html b/files/zh-cn/web/javascript/reference/global_objects/symbol/species/index.html new file mode 100644 index 0000000000..aeb9918a47 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/symbol/species/index.html @@ -0,0 +1,73 @@ +--- +title: Symbol.species +slug: Web/JavaScript/Reference/Global_Objects/Symbol/species +tags: + - ECMAScript 2015 + - JavaScript + - Property + - Symbol +translation_of: Web/JavaScript/Reference/Global_Objects/Symbol/species +--- +<div>{{JSRef}}</div> + +<p>知名的<strong> </strong><code><strong>Symbol.species</strong></code> 是个函数值属性,其被构造函数用以创建派生对象。</p> + +<div>{{EmbedInteractiveExample("pages/js/symbol-species.html")}}</div> + + + +<div>{{js_property_attributes(0,0,0)}}</div> + +<h2 id="描述">描述</h2> + +<p>species 访问器属性允许子类覆盖对象的默认构造函数。</p> + +<h2 id="示例">示例</h2> + +<p>你可能想在扩展数组类 <code>MyArray </code>上返回 {{jsxref("Array")}} 对象。 例如,当使用例如 {{jsxref("Array.map", "map()")}} 这样的方法返回默认的构造函数时,你希望这些方法能够返回父级的 Array 对象,以取代 <code>MyArray</code> 对象。<code>Symbol.species</code> 允许你这么做:</p> + +<pre class="brush: js">class MyArray extends Array { + // 覆盖 species 到父级的 Array 构造函数上 + static get [Symbol.species]() { return Array; } +} +var a = new MyArray(1,2,3); +var mapped = a.map(x => x * x); + +console.log(mapped instanceof MyArray); // false +console.log(mapped instanceof Array); // true +</pre> + +<h2 id="规范">规范</h2> + +<table class="standard-table"> + <tbody> + <tr> + <th scope="col">Specification</th> + <th scope="col">Status</th> + <th scope="col">Comment</th> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-symbol.species', 'Symbol.species')}}</td> + <td>{{Spec2('ES6')}}</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-symbol.species', 'Symbol.species')}}</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.Symbol.species")}}</p> + +<h2 id="相关链接">相关链接</h2> + +<ul> + <li>{{jsxref("Map.@@species", "Map[@@species]")}}</li> + <li>{{jsxref("Set.@@species", "Set[@@species]")}}</li> +</ul> |