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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/proxy/handler/ownkeys | |
| parent | 8b66d724f7caf0157093fb09cfec8fbd0c6ad50a (diff) | |
| download | translated-content-33058f2b292b3a581333bdfb21b8f671898c5060.tar.gz translated-content-33058f2b292b3a581333bdfb21b8f671898c5060.tar.bz2 translated-content-33058f2b292b3a581333bdfb21b8f671898c5060.zip | |
initial commit
Diffstat (limited to 'files/zh-cn/web/javascript/reference/global_objects/proxy/handler/ownkeys')
| -rw-r--r-- | files/zh-cn/web/javascript/reference/global_objects/proxy/handler/ownkeys/index.html | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/files/zh-cn/web/javascript/reference/global_objects/proxy/handler/ownkeys/index.html b/files/zh-cn/web/javascript/reference/global_objects/proxy/handler/ownkeys/index.html new file mode 100644 index 0000000000..956b908375 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/proxy/handler/ownkeys/index.html @@ -0,0 +1,193 @@ +--- +title: handler.ownKeys() +slug: Web/JavaScript/Reference/Global_Objects/Proxy/handler/ownKeys +translation_of: Web/JavaScript/Reference/Global_Objects/Proxy/Proxy/ownKeys +--- +<div>{{JSRef}}</div> + +<p><strong><code>handler.ownKeys()</code></strong> 方法用于拦截 {{jsxref("Reflect.ownKeys()")}}.</p> + + + +<p>{{EmbedInteractiveExample("pages/js/proxyhandler-ownkeys.html", "taller")}}</p> + + + +<h2 id="语法">语法</h2> + +<pre class="brush: js">var p = new Proxy(target, { + ownKeys: function(target) { + } +}); +</pre> + +<h3 id="参数">参数</h3> + +<p>下面的参数被传递给<code>ownKeys。this</code>被绑定在<code>handler上。</code></p> + +<dl> + <dt><code>target</code></dt> + <dd>目标对象.</dd> +</dl> + +<h3 id="返回值">返回值</h3> + +<p><code>ownKeys</code> 方法必须返回一个可枚举对象.</p> + +<h2 id="描述">描述</h2> + +<p><code><strong>handler.ownKeys()</strong></code> 方法用于拦截 {{jsxref("Reflect.ownKeys()")}}.</p> + +<h3 id="拦截">拦截</h3> + +<p>该拦截器可以拦截以下操作::</p> + +<ul> + <li>{{jsxref("Object.getOwnPropertyNames()")}}</li> + <li>{{jsxref("Object.getOwnPropertySymbols()")}}</li> + <li>{{jsxref("Object.keys()")}}</li> + <li>{{jsxref("Reflect.ownKeys()")}}</li> +</ul> + +<h3 id="约束">约束</h3> + +<p>如果违反了下面的约束,proxy将抛出错误 {{jsxref("TypeError")}}:</p> + +<ul> + <li><code>ownKeys</code> 的结果必须是一个数组.</li> + <li>数组的元素类型要么是一个 {{jsxref("String")}} ,要么是一个 {{jsxref("Symbol")}}.</li> + <li>结果列表必须包含目标对象的所有不可配置(non-configurable )、自有(own)属性的key.</li> + <li>如果目标对象不可扩展,那么结果列表必须包含目标对象的所有自有(own)属性的key,不能有其它值.</li> +</ul> + +<h2 id="示例">示例</h2> + +<p>下面的代码拦截 {{jsxref("Object.getOwnPropertyNames()")}}.</p> + +<pre class="brush: js">var p = new Proxy({}, { + ownKeys: function(target) { + console.log('called'); + return ['a', 'b', 'c']; + } +}); + +console.log(Object.getOwnPropertyNames(p)); // "called" + // [ 'a', 'b', 'c' ]</pre> + +<p>下面的代码违反了约定</p> + +<pre class="brush: js example-bad">var obj = {}; +Object.defineProperty(obj, 'a', { + configurable: false, + enumerable: true, + value: 10 } +); + +var p = new Proxy(obj, { + ownKeys: function(target) { + return [123, 12.5, true, false, undefined, null, {}, []]; + } +}); + +console.log(Object.getOwnPropertyNames(p)); + +// TypeError: proxy [[OwnPropertyKeys]] 必须返回一个数组 +// 数组元素类型只能是String或Symbol +</pre> + +<h2 id="标准">标准</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('ES2015', '#sec-proxy-object-internal-methods-and-internal-slots-ownpropertykeys', '[[OwnPropertyKeys]]')}}</td> + <td>{{Spec2('ES2015')}}</td> + <td>Initial definition.</td> + </tr> + <tr> + <td>{{SpecName('ESDraft', '#sec-proxy-object-internal-methods-and-internal-slots-ownpropertykeys', '[[OwnPropertyKeys]]')}}</td> + <td>{{Spec2('ESDraft')}}</td> + <td></td> + </tr> + </tbody> +</table> + +<h2 id="浏览器兼容">浏览器兼容</h2> + +<div>{{CompatibilityTable}}</div> + +<div id="compat-desktop"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Chrome</th> + <th>Firefox (Gecko)</th> + <th>Internet Explorer</th> + <th>Opera</th> + <th>Safari</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatGeckoDesktop("18")}}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + </tr> + </tbody> +</table> +</div> + +<div id="compat-mobile"> +<table class="compat-table"> + <tbody> + <tr> + <th>Feature</th> + <th>Android</th> + <th>Chrome for Android</th> + <th>Firefox Mobile (Gecko)</th> + <th>IE Mobile</th> + <th>Opera Mobile</th> + <th>Safari Mobile</th> + </tr> + <tr> + <td>Basic support</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatGeckoMobile("18")}}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + <td>{{CompatUnknown}}</td> + </tr> + </tbody> +</table> +</div> + +<h2 id="兼容性注意事项">兼容性注意事项</h2> + +<h3 id="Firefox火狐">Firefox火狐</h3> + +<ul> + <li>在Gecko 42 {{geckoRelease(42)}}版本中, <code>ownKey</code> 的实施已经更新了,为了反映最终的ES5标准 (see {{bug(1049662)}}): + + <ul> + <li>现在需要检查结果是不是数组以及数组元素类型是不是string或symbol.</li> + <li>枚举重复的自有的属性名称不再失败.</li> + </ul> + </li> +</ul> + +<h2 id="另见">另见</h2> + +<ul> + <li>{{jsxref("Proxy")}}</li> + <li>{{jsxref("Proxy.handler", "handler")}}</li> + <li>{{jsxref("Object.getOwnPropertyNames()")}}</li> + <li>{{jsxref("Reflect.ownKeys()")}}</li> +</ul> |
