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diff --git a/files/zh-cn/web/javascript/reference/global_objects/array/isarray/index.html b/files/zh-cn/web/javascript/reference/global_objects/array/isarray/index.html new file mode 100644 index 0000000000..817312bc5c --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/array/isarray/index.html @@ -0,0 +1,140 @@ +--- +title: Array.isArray() +slug: Web/JavaScript/Reference/Global_Objects/Array/isArray +tags: + - ECMAScript5 + - JavaScript + - 'brush: js' + - class= + - polyfill + - 数组 + - 方法 +translation_of: Web/JavaScript/Reference/Global_Objects/Array/isArray +--- +<div>{{JSRef}}</div> + +<p><strong>Array.isArray() </strong>用于确定传递的值是否是一个 {{jsxref("Array")}}。</p> + +<pre class="brush: js">Array.isArray([1, 2, 3]); +// true +Array.isArray({foo: 123}); +// false +Array.isArray("foobar"); +// false +Array.isArray(undefined); +// false +</pre> + +<h2 id="语法">语法</h2> + +<pre>Array.isArray(<var>obj</var>)</pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>obj</code></dt> + <dd>需要检测的值。</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>如果值是 {{jsxref("Array")}},则为true; 否则为false。</p> + +<h2 id="描述">描述</h2> + +<p>如果对象是 {{jsxref("Array")}} ,则返回true,否则为false。</p> + +<p>有关更多详细信息,请参阅文章<a href="http://web.mit.edu/jwalden/www/isArray.html">严格判定JavaScript对象是否为数组</a>。</p> + +<p>See the article <a href="http://web.mit.edu/jwalden/www/isArray.html">“Determining with absolute accuracy whether or not a JavaScript object is an array”</a> for more details. Given a {{jsxref("TypedArray")}} instance, <code>false</code> is always returned.</p> + +<h2 id="示例">示例</h2> + +<pre class="brush: js">// 下面的函数调用都返回 true +Array.isArray([]); +Array.isArray([1]); +Array.isArray(new Array()); +Array.isArray(new Array('a', 'b', 'c', 'd')) +// 鲜为人知的事实:其实 Array.prototype 也是一个数组。 +Array.isArray(Array.prototype); + +// 下面的函数调用都返回 false +Array.isArray(); +Array.isArray({}); +Array.isArray(null); +Array.isArray(undefined); +Array.isArray(17); +Array.isArray('Array'); +Array.isArray(true); +Array.isArray(false); +Array.isArray(new Uint8Array(32)) +Array.isArray({ __proto__: Array.prototype }); +</pre> + +<h3 id="instanceof_和_isArray"><code>instanceof</code> 和 <code>isArray</code></h3> + +<p>当检测Array实例时, <code>Array.isArray</code> 优于 <code>instanceof</code>,因为Array.isArray能检测<code>iframes</code>.</p> + +<pre><code>var iframe = document.createElement('iframe'); +document.body.appendChild(iframe); +xArray = window.frames[window.frames.length-1].Array; +var arr = new xArray(1,2,3); // [1,2,3] + +// Correctly checking for Array +Array.isArray(arr); // true +// Considered harmful, because doesn't work though iframes +arr instanceof Array; // false</code></pre> + +<h2 id="Polyfill">Polyfill</h2> + +<p>假如不存在 Array.isArray(),则在其他代码之前运行下面的代码将创建该方法。</p> + +<pre class="brush: js">if (!Array.isArray) { + Array.isArray = function(arg) { + return Object.prototype.toString.call(arg) === '[object Array]'; + }; +} +</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('ES5.1', '#sec-15.4.3.2', 'Array.isArray')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td>Initial definition. Implemented in JavaScript 1.8.5.</td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-array.isarray', 'Array.isArray')}}</td> + <td>{{Spec2('ES6')}}</td> + <td></td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-array.isarray', 'Array.isArray')}}</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> + +<div> +<div> + + +<p>{{Compat("javascript.builtins.Array.isArray")}}</p> +</div> +</div> + +<h2 id="相关链接">相关链接</h2> + +<ul> + <li>{{jsxref("Array")}}</li> +</ul> |