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---
title: WebAssembly.Table()
slug: Web/JavaScript/Reference/Global_Objects/WebAssembly/Table
translation_of: Web/JavaScript/Reference/Global_Objects/WebAssembly/Table
---
<div>{{JSRef}}</div>
<p><code><strong>WebAssembly.Table()</strong></code> 构造函数根据给定的大小和元素类型创建一个Table对象。 </p>
<p>这是一个包装了WebAssemble Table 的Javascript包装对象，具有类数组结构，存储了多个函数引用。在Javascript或者WebAssemble中创建Table 对象可以同时被Javascript或WebAssemble 访问和更改。</p>
<div class="note">
<p><strong>Note</strong>: Tables 对象目前只能存储函数引用，不过在将来可能会被扩展。</p>
</div>
<h2 id="语法">语法</h2>
<pre class="syntaxbox">var myTable = new WebAssembly.Table(tableDescriptor);</pre>
<h3 id="参数">参数</h3>
<dl>
<dt><em>tableDescriptor</em></dt>
<dd>该对象具有以下属性：
<dl>
<dt><em>element</em></dt>
<dd>一个表明储存在该Table中对象的类型。 目前只能是： <code>"anyfunc"</code> (函数)。</dd>
<dt><em>initial</em></dt>
<dd>该WebAssembly Table初始大小。</dd>
<dt><em>maximum {{optional_inline}}</em></dt>
<dd>该WebAssembly Table允许扩展到的最大大小。</dd>
</dl>
</dd>
</dl>
<h3 id="异常">异常</h3>
<ul>
<li>如果 <code>tableDescriptor</code> 不是对象类型, 将会抛出 {{jsxref("TypeError")}} 异常。</li>
<li>如果申明了 <code>maximum</code> 属性并且比 <code>initial小</code>, 将会抛出{{jsxref("RangeError")}} 异常。</li>
</ul>
<h2 id="Table_Instance"><code>Table</code> Instance</h2>
<p>所有<code>Table</code>实例都继承自<code>Table()</code>构造函数的<a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/WebAssembly/Table/prototype">原型对象</a>-可以对其进行修改以影响所有<code>Table</code>实例。</p>
<h3 id="Instance_属性">Instance 属性</h3>
<dl>
<dt><code>Table.prototype.constructor</code></dt>
<dd>返回创建该对象实例的函数。默认情况下，这是{{jsxref("WebAssembly.Table()")}} 的构造函数。</dd>
<dt>{{jsxref("WebAssembly/Table/length","Table.prototype.length")}}</dt>
<dd>返回Table的长度，即元素数。</dd>
</dl>
<h3 id="Instance_methods">Instance methods</h3>
<dl>
<dt>{{jsxref("WebAssembly/Table/get","Table.prototype.get()")}}</dt>
<dd>Accessor function — gets the element stored at a given index.</dd>
<dt>{{jsxref("WebAssembly/Table/grow","Table.prototype.grow()")}}</dt>
<dd>Increases the size of the Table instance by a specified number of elements.</dd>
<dt>{{jsxref("WebAssembly/Table/set","Table.prototype.set()")}}</dt>
<dd>Sets an element stored at a given index to a given value.</dd>
</dl>
<h2 id="例子">例子</h2>
<p>The following example (see table2.html <a href="https://github.com/mdn/webassembly-examples/blob/master/js-api-examples/table2.html">source code</a> and <a href="https://mdn.github.io/webassembly-examples/js-api-examples/table2.html">live version</a>) creates a new WebAssembly Table instance with an initial size of 2 elements. We then print out the table length and contents of the two indexes (retrieved via {{jsxref("WebAssembly/Table/get", "Table.prototype.get()")}} to show that the length is two and both elements are {{jsxref("null")}}.</p>
<pre class="brush: js">var tbl = new WebAssembly.Table({initial:2, element:"anyfunc"});
console.log(tbl.length); // "2"
console.log(tbl.get(0)); // "null"
console.log(tbl.get(1)); // "null"</pre>
<p>We then create an import object that contains the table:</p>
<pre class="brush: js">var importObj = {
js: {
tbl:tbl
}
};</pre>
<p>Finally, we load and instantiate a wasm module (table2.wasm) using the {{jsxref("WebAssembly.instantiateStreaming()")}} method. The table2.wasm module contains two functions (one that returns 42 and another that returns 83) and stores both into elements 0 and 1 of the imported table (see <a href="https://github.com/mdn/webassembly-examples/blob/master/js-api-examples/table2.wat">text representation</a>). So after instantiation, the table still has length 2, but the elements now contain callable <a href="/en-US/docs/WebAssembly/Exported_functions">Exported WebAssembly Functions</a> which we can call from JS.</p>
<pre class="brush: js">WebAssembly.instantiateStreaming(fetch('table2.wasm'), importObject)
.then(function(obj) {
console.log(tbl.length);
console.log(tbl.get(0)());
console.log(tbl.get(1)());
});</pre>
<p>Note how you've got to include a second function invocation operator at the end of the accessor to actually invoke the referenced function and log the value stored inside it (e.g. <code>get(0)()</code> rather than <code>get(0)</code>) .</p>
<p>This example shows that we're creating and accessing the table from JavaScript, but the same table is visible and callable inside the wasm instance too.</p>
<h2 id="规范">规范</h2>
<table class="standard-table">
<thead>
<tr>
<th scope="col">规范</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
</thead>
<tbody>
<tr>
<td>{{SpecName('WebAssembly JS', '#webassemblytable-objects', 'Table')}}</td>
<td>{{Spec2('WebAssembly JS')}}</td>
<td>Initial draft definition.</td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility">浏览器兼容性</h2>
<div>
<p>{{Compat("javascript.builtins.WebAssembly.Table")}}</p>
</div>
<h2 id="相关链接">相关链接</h2>
<ul>
<li><a href="/en-US/docs/WebAssembly">WebAssembly</a> overview page</li>
<li><a href="/en-US/docs/WebAssembly/Concepts">WebAssembly concepts</a></li>
<li><a href="/en-US/docs/WebAssembly/Using_the_JavaScript_API">Using the WebAssembly JavaScript API</a></li>
</ul>
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