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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/observe/index.html | |
| parent | 8b66d724f7caf0157093fb09cfec8fbd0c6ad50a (diff) | |
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diff --git a/files/zh-cn/web/javascript/reference/global_objects/array/observe/index.html b/files/zh-cn/web/javascript/reference/global_objects/array/observe/index.html new file mode 100644 index 0000000000..7c2dcc8474 --- /dev/null +++ b/files/zh-cn/web/javascript/reference/global_objects/array/observe/index.html @@ -0,0 +1,92 @@ +--- +title: Array.observe() +slug: Web/JavaScript/Reference/Global_Objects/Array/observe +tags: + - JavaScript + - 实验性 + - 数组 + - 方法 + - 过时的 +translation_of: Archive/Web/JavaScript/Array.observe +--- +<div>{{JSRef}}{{obsolete_header}}</div> + +<p><strong>Array.observe()</strong> 方法用于异步监视数组发生的变化,类似于针对对象的 {{jsxref("Object.observe()")}} 。当数组的值发生变化时,它按发生顺序提供了一个变化流。与 <code>Object.observe()</code> 类似,它由如下可接受的变化类型列表<code>["add"、"update"、"delete"、"splice"]</code>触发。</p> + +<h2 id="语法">语法</h2> + +<pre class="syntaxbox"><code>Array.observe(<var>arr</var>, <var>callback</var>)</code></pre> + +<h3 id="参数">参数</h3> + +<dl> + <dt><code>arr</code></dt> + <dd>用于被监视的数组</dd> + <dt><code>callback</code></dt> + <dd>每当数组发生变化时,使用如下参数调用该函数: + <dl> + <dt><code>changes</code></dt> + <dd>用于表示变化的对象数组。每个变化对象的属性如下: + <ul> + <li><strong><code>name</code></strong>: 变化的属性名。</li> + <li><strong><code>object</code></strong>: 变化后的数组。</li> + <li><strong><code>type</code></strong>: 用于表示变化类型的字符串。<code>其取值为"add"、</code><code>"update"、</code><code>"delete"</code>或 <code>"splice"</code>之一。</li> + <li><strong><code>oldValue</code></strong>: 仅用于<code>"update"</code>和<code>"delete"类型。变化</code>之前的取值。</li> + <li><strong><code>index</code></strong>: <code>仅用于"splice"类型。</code>变化发生所在索引。</li> + <li><strong><code>removed</code></strong>: 仅用于<code>"splice"类型。</code>被删除元素组成的数组。</li> + <li><strong><code>addedCount</code></strong>: 仅用于<code>"splice"</code>类型。被添加的元素数量。</li> + </ul> + </dd> + </dl> + </dd> +</dl> + +<h2 id="描述">描述</h2> + +<p>每次 arr 发生任何变化时,回调函数将被调用,调用参数为所有变化按发生顺序组成的数组。</p> + +<div class="note"> +<p>通过Array方法如<a href="https://developer.mozilla.org/zh-CN/docs/Web/JavaScript/Reference/Global_Objects/Array/pop"> Array.prototype.pop( )</a> 触发的变化将被报告成"<em>splice</em>"变化,长度不变但索引赋值发生变化的将被报告成"update"变化。</p> +</div> + +<h2 id="示例">示例</h2> + +<h3 id="Example_Logging_different_change_types">Example: Logging different change types</h3> + +<pre class="brush: js">var arr = ['a', 'b', 'c']; + +Array.observe(arr, function(changes) { + console.log(changes); +}); + +arr[1] = 'B'; +// [{type: 'update', object: <arr>, name: '1', oldValue: 'b'}] + +arr[3] = 'd'; +// [{type: 'splice', object: <arr>, index: 3, removed: [], addedCount: 1}] + +arr.splice(1, 2, 'beta', 'gamma', 'delta'); +// [{type: 'splice', object: <arr>, index: 1, removed: ['B', 'c'], addedCount: 3}] +</pre> + +<h2 id="Specifications" name="Specifications">标准规范</h2> + +<p><a href="https://github.com/arv/ecmascript-object-observe">Strawman proposal specification</a>.</p> + +<h2 id="Browser_compatibility" name="Browser_compatibility">浏览器支持</h2> + +<div> +<div> + + +<p>{{Compat("javascript.builtins.Array.observe")}}</p> +</div> +</div> + +<h2 id="See_also" name="See_also">相关内容</h2> + +<ul> + <li>{{jsxref("Array.unobserve()")}} {{experimental_inline}}</li> + <li>{{jsxref("Object.observe()")}} {{experimental_inline}}</li> + <li><a href="https://stackoverflow.com/q/29269057/778272">Under what condition would Array.observe's “add” event trigger?</a></li> +</ul> |
