diff options
Diffstat (limited to 'files/zh-cn/web/javascript/reference/global_objects/object/getownpropertynames/index.html')
| -rw-r--r-- | files/zh-cn/web/javascript/reference/global_objects/object/getownpropertynames/index.html | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/files/zh-cn/web/javascript/reference/global_objects/object/getownpropertynames/index.html b/files/zh-cn/web/javascript/reference/global_objects/object/getownpropertynames/index.html new file mode 100644 index 0000000000..996a67689e --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/object/getownpropertynames/index.html @@ -0,0 +1,169 @@ +--- +title: Object.getOwnPropertyNames() +slug: Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames +tags: + - ECMAScript 5 + - JavaScript + - JavaScript 1.8.5 + - Method + - Object + - Reference +translation_of: Web/JavaScript/Reference/Global_Objects/Object/getOwnPropertyNames +--- +<div>{{JSRef}}</div> + +<p><strong><code>Object.getOwnPropertyNames()</code></strong>方法返回一个由指定对象的所有自身属性的属性名（包括不可枚举属性但不包括Symbol值作为名称的属性）组成的数组。</p> + +<h2 id="Syntax" name="Syntax">语法</h2> + +<pre class="syntaxbox">Object.getOwnPropertyNames(<em>obj</em>)</pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>obj</code></dt> + <dd>一个对象，其自身的可枚举和不可枚举属性的名称被返回。</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p>在给定对象上找到的自身属性对应的字符串数组。</p> + +<h2 id="Description" name="Description" style="margin-bottom: 20px; line-height: 30px;">描述</h2> + +<p><code>Object.getOwnPropertyNames()</code> 返回一个数组，该数组对元素是 <code>obj</code>自身拥有的枚举或不可枚举属性名称字符串。 数组中枚举属性的顺序与通过 {{jsxref("Statements/for...in", "for...in")}} 循环（或 {{jsxref("Object.keys")}}）迭代该对象属性时一致。数组中不可枚举属性的顺序未定义。</p> + +<h2 id="示例">示例</h2> + +<h3 id="使用_Object.getOwnPropertyNames()">使用 <code>Object.getOwnPropertyNames()</code></h3> + +<pre class="brush: js">var arr = ["a", "b", "c"]; +console.log(Object.getOwnPropertyNames(arr).sort()); // ["0", "1", "2", "length"] + +// 类数组对象 +var obj = { 0: "a", 1: "b", 2: "c"}; +console.log(Object.getOwnPropertyNames(obj).sort()); // ["0", "1", "2"] + +// 使用Array.forEach输出属性名和属性值 +Object.getOwnPropertyNames(obj).forEach(function(val, idx, array) { + console.log(val + " -> " + obj[val]); +}); +// 输出 +// 0 -> a +// 1 -> b +// 2 -> c + +//不可枚举属性 +var my_obj = Object.create({}, { + getFoo: { + value: function() { return this.foo; }, + enumerable: false + } +}); +my_obj.foo = 1; + +console.log(Object.getOwnPropertyNames(my_obj).sort()); // ["foo", "getFoo"] +</pre> + +<p>如果你只要获取到可枚举属性，查看{{jsxref("Object.keys")}}或用{{jsxref("Statements/for...in", "for...in")}}循环（还会获取到原型链上的可枚举属性，不过可以使用{{jsxref("Object.prototype.hasOwnProperty()", "hasOwnProperty()")}}方法过滤掉）。</p> + +<p>下面的例子演示了该方法不会获取到原型链上的属性：</p> + +<pre class="brush: js">function ParentClass() {} +ParentClass.prototype.inheritedMethod = function() {}; + +function ChildClass() { + this.prop = 5; + this.method = function() {}; +} + +ChildClass.prototype = new ParentClass; +ChildClass.prototype.prototypeMethod = function() {}; + +console.log( + Object.getOwnPropertyNames( + new ChildClass() // ["prop", "method"] + ) +); +</pre> + +<h3 id="只获取不可枚举的属性">只获取不可枚举的属性</h3> + +<p>下面的例子使用了 {{jsxref("Array.prototype.filter()")}} 方法，从所有的属性名数组（使用<code>Object.getOwnPropertyNames()</code>方法获得）中去除可枚举的属性（使用{{jsxref("Object.keys()")}}方法获得），剩余的属性便是不可枚举的属性了：</p> + +<pre class="brush: js">var target = myObject; +var enum_and_nonenum = Object.getOwnPropertyNames(target); +var enum_only = Object.keys(target); +var nonenum_only = enum_and_nonenum.filter(function(key) { + var indexInEnum = enum_only.indexOf(key); + if (indexInEnum == -1) { + // 没有发现在enum_only健集中意味着这个健是不可枚举的, + // 因此返回true 以便让它保持在过滤结果中 + return true; + } else { + return false; + } +}); + +console.log(nonenum_only);</pre> + +<pre>注：<a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Array/filter">Array.filter(filt_func)方法</a>创建一个新数组, 其包含通过所提供函数实现的测试的所有元素。</pre> + +<h2 id="Notes" name="Notes">提示</h2> + +<p>在 ES5 中，如果参数不是一个原始对象类型，将抛出一个 {{jsxref("TypeError")}} 异常。在 ES2015 中，非对象参数被强制转换为对象 <strong>。</strong></p> + +<pre class="brush: js">Object.getOwnPropertyNames('foo'); +// TypeError: "foo" is not an object (ES5 code) + +Object.getOwnPropertyNames('foo'); +// ['length', '0', '1', '2'] (ES2015 code) +</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-15.2.3.4', 'Object.getOwnPropertyNames')}}</td> + <td>{{Spec2('ES5.1')}}</td> + <td>Initial definition. Implemented in JavaScript 1.8.5.</td> + </tr> + <tr> + <td>{{SpecName('ES6', '#sec-object.getownpropertynames', 'Object.getOwnPropertyNames')}}</td> + <td>{{Spec2('ES6')}}</td> + <td> </td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-object.getownpropertynames', 'Object.getOwnPropertyNames')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td> </td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容">浏览器兼容</h2> + +<div class="hidden">The compatibility table on this page is generated from structured data. If you'd like to contribute to the data, please check out <a href="https://github.com/mdn/browser-compat-data">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</div> + +<p>{{Compat("javascript.builtins.Object.getOwnPropertyNames")}}</p> + +<h2 id="Firefox-specific_notes">Firefox-specific notes</h2> + +<p>Firefox 28 {{geckoRelease("28")}}之前，<code>Object.getOwnPropertyNames</code> 不会获取到 {{jsxref("Error")}} 对象的属性。该 bug 在后面的版本修复了 ({{bug("724768")}})。</p> + +<h2 id="See_also" name="See_also" style="margin-bottom: 20px; line-height: 30px;">相关链接</h2> + +<ul> + <li><a href="https://developer.mozilla.org/en-US/docs/Enumerability_and_ownership_of_properties" title="Enumerability_and_ownership_of_properties">Enumerability and ownership of properties</a></li> + <li>{{jsxref("Object.prototype.hasOwnProperty")}}</li> + <li>{{jsxref("Object.prototype.propertyIsEnumerable")}}</li> + <li>{{jsxref("Object.create")}}</li> + <li>{{jsxref("Object.keys")}}</li> + <li>{{jsxref("Array.forEach()")}}</li> +</ul> |