uTools-Manuals/docs/javascript/Reference/Statements/function-.html

<article id="wikiArticle">
<div></div>
<p><code><strong>function*</strong></code> 这种声明方式(<code style="font-style: normal;">function</code>关键字后跟一个星号）会定义一个<strong><em>生成器函数</em> (</strong><em>generator function</em><strong>)</strong>，它返回一个  <a href="Reference/Global_Objects/Generator" title="生成器对象是由一个 generator function 返回的,并且它符合可迭代协议和迭代器协议。"><code>Generator</code></a>  对象。</p>
<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/statement-functionasterisk.html" width="100%"></iframe></div>
<p class="hidden">The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone <a class="external" href="https://github.com/mdn/interactive-examples" rel="noopener">https://github.com/mdn/interactive-examples</a> and send us a pull request.</p>
<div class="noinclude">
<p>你也可以使用构造函数  <a href="Reference/Global_Objects/GeneratorFunction" title="GeneratorFunction构造器生成新的生成器函数 对象。在JavaScript中，生成器函数实际上都是GeneratorFunction的实例对象。"><code>GeneratorFunction</code></a> 或 <a href="Reference/Operators/function*" title="function*关键字可以在表达式内部定义一个生成器函数。"><code>function* expression</code></a> 定义<strong><em>生成器函数</em> </strong>。</p>
</div>
<h2 id="语法">语法</h2>
<pre><code class="language-javascript">function* <em>name</em>([<em>param</em>[, <em>param</em>[, ... <em>param</em>]]]) { <em>statements</em> }
</code></pre>
<dl>
<dt><code>name</code></dt>
<dd>函数名</dd>
</dl>
<dl>
<dt><code>param</code></dt>
<dd>要传递给函数的一个参数的名称，一个函数最多可以有255个参数。</dd>
</dl>
<dl>
<dt><code>statements</code></dt>
<dd>普通JS语句。</dd>
</dl>
<h2 id="描述">描述</h2>
<p><strong>生成器函数</strong>在执行时能暂停，后面又能从暂停处继续执行。</p>
<p>调用一个<strong>生成器函数</strong>并不会马上执行它里面的语句，而是返回一个这个生成器的 <strong>迭代器</strong> <strong><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#iterator">（iterator</a> ）对象</strong>。当这个迭代器的 <code>next() </code>方法被首次（后续）调用时，其内的语句会执行到第一个（后续）出现<a href="Reference/Operators/yield" title="yield 关键字用来暂停和恢复一个生成器函数（(function* 或遗留的生成器函数）。"><code>yield</code></a>的位置为止，<a href="Reference/Operators/yield" title="yield 关键字用来暂停和恢复一个生成器函数（(function* 或遗留的生成器函数）。"><code>yield</code></a> 后紧跟迭代器要返回的值。或者如果用的是 <a href="Reference/Operators/yield*" title="yield* 表达式用于委托给另一个generator 或可迭代对象。"><code>yield*</code></a>（多了个星号），则表示将执行权移交给另一个生成器函数（当前生成器暂停执行）。</p>
<p><code>next()</code>方法返回一个对象，这个对象包含两个属性：value 和 done，value 属性表示本次 <code>yield </code>表达式的返回值，done 属性为布尔类型，表示生成器后续是否还有<code> yield </code>语句，即生成器函数是否已经执行完毕并返回。</p>
<p>调用 <code>next()</code>方法时，如果传入了参数，那么这个参数会作为<strong>上一条执行的  yield 语句的返回值</strong>，例如：</p>
<pre><code  class="language-javascript">function *gen(){
    yield 10;
    y=yield 'foo';
    yield y;
}

var gen_obj=gen();
console.log(gen_obj.next());// 执行 yield 10，返回 10
console.log(gen_obj.next());// 执行 yield 'foo'，返回 'foo'
console.log(gen_obj.next(10));// 将 10 赋给上一条 yield 'foo' 的左值，即执行 y=10，返回 10
console.log(gen_obj.next());// 执行完毕，value 为 undefined，done 为 true</code></pre>
<p>当在生成器函数中显式 <code>return </code>时，会导致生成器立即变为完成状态，即调用 <code>next()</code> 方法返回的对象的 <code>done </code>为 <code>true</code>。如果 <code>return </code>后面跟了一个值，那么这个值会作为<strong>当前</strong>调用 <code>next()</code> 方法返回的 value 值。</p>
<h2 id="示例">示例</h2>
<h3 id="简单示例">简单示例</h3>
<pre><code  class="language-javascript">function* idMaker(){
  var index = 0;
  while(index&lt;3)
    yield index++;
}

var gen = idMaker();
console.log(gen.next().value); // 0
console.log(gen.next().value); // 1
console.log(gen.next().value); // 2
console.log(gen.next().value); // undefined
</code></pre>
<h3 id="生成器也可以接收参数：">生成器也可以接收参数：</h3>
<pre><code  class="language-javascript">function* idMaker(){
    var index = arguments[0] || 0;
    while(true)
        yield index++;
}

var gen = idMaker(5);
console.log(gen.next().value); // 5
console.log(gen.next().value); // 6</code></pre>
<h3 id="yield*的示例">yield*的示例</h3>
<pre><code  class="language-javascript">function* anotherGenerator(<strong>i</strong>) {
  yield i + 1;
  yield i + 2;
  yield i + 3;
}

function* generator(<strong>i</strong>){
  yield i;
  yield* anotherGenerator(<strong>i</strong>);// 移交执行权
  yield i + 10;
}

var gen = generator(10);

console.log(gen.next().value); // 10
console.log(gen.next().value); // 11
console.log(gen.next().value); // 12
console.log(gen.next().value); // 13
console.log(gen.next().value); // 20
</code></pre>
<h3 id="传递参数">传递参数</h3>
<pre><code  class="language-javascript">function *createIterator() {
    let first = yield 1;
    let second = yield first + 2; // <strong>4</strong> + 2 
                                  // first =4 是next<strong>(4)将参数赋给上一条的</strong>
    yield second + 3;             // <strong>5</strong> + 3
}

let iterator = createIterator();

console.log(iterator.next());    // "{ value: 1, done: false }"
console.log(iterator.next<strong>(4)</strong>);   // "{ value: 6, done: false }"
console.log(iterator.next(<strong>5</strong>));   // "{ value: 8, done: false }"
console.log(iterator.next());    // "{ value: undefined, done: true }"</code></pre>
<h3 id="显式返回">显式返回</h3>
<pre><code  class="language-javascript">function* yieldAndReturn() {
  yield "Y";
  return "R";//显式返回处，可以观察到 done 也立即变为了 true
  yield "unreachable";// 不会被执行了
}

var gen = yieldAndReturn()
console.log(gen.next()); // { value: "Y", done: false }
console.log(gen.next()); // { value: "R", done: true }
console.log(gen.next()); // { value: undefined, done: true }</code></pre>
<h3 id="生成器函数不能当构造器使用">生成器函数不能当构造器使用</h3>
<pre><code  class="language-javascript">function* f() {}
var obj = new f; // throws "TypeError: f is not a constructor"</code></pre>
<h3 id="使用迭代器遍历二维数组并转换成一维数组：">使用迭代器遍历二维数组并转换成一维数组：</h3>
<blockquote>
<pre><code  class="language-javascript">function* iterArr(arr) {            //迭代器返回一个迭代器对象
  if (Array.isArray(arr)) {         // 内节点
      for(let i=0; i &lt; arr.length; i++) {
          yield* iterArr(arr[i]);   // (*)递归
      }
  } else {                          // 离开     
      yield arr;
  }
}
// 使用 for-of 遍历:
var arr = ['a', ['b', 'c'], ['d', 'e']];
for(var x of iterArr(arr)) {
        console.log(x);               // a  b  c  d  e
 }

// 或者直接将迭代器展开:
var arr = [ 'a', ['b',[ 'c', ['d', 'e']]]];
var gen = iterArr(arr);
arr = [...gen];                        // ["a", "b", "c", "d", "e"]</code></pre>
</blockquote>
<h2 id="规范">规范</h2>
<table class="standard-table">
<thead>
<tr>
<th scope="col">Specification</th>
<th scope="col">Status</th>
<th scope="col">Comment</th>
</tr>
</thead>
<tbody>
<tr>
<td><a class="external" href="https://www.ecma-international.org/ecma-262/6.0/#" hreflang="en" lang="en" rel="noopener">ECMAScript 2015 (6th Edition, ECMA-262)<br/><small lang="zh-CN">function*</small></a></td>
<td><span class="spec-Standard">Standard</span></td>
<td>Initial definition.</td>
</tr>
<tr>
<td><a class="external" href="https://tc39.github.io/ecma262/#" hreflang="en" lang="en" rel="noopener">ECMAScript Latest Draft (ECMA-262)<br/><small lang="zh-CN">function*</small></a></td>
<td><span class="spec-Draft">Draft</span></td>
<td> </td>
</tr>
</tbody>
</table>
<h2 id="浏览器兼容性">浏览器兼容性</h2>
<div>
<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 class="external" href="https://github.com/mdn/browser-compat-data" rel="noopener">https://github.com/mdn/browser-compat-data</a> and send us a pull request.</div>
<p></p><div class="bc-data"><a class="bc-github-link external" href="https://github.com/mdn/browser-compat-data" rel="noopener">Update compatibility data on GitHub</a><table class="bc-table bc-table-js"><thead><tr class="bc-platforms"><td></td><th class="bc-platform-desktop" colspan="6"><span>Desktop</span></th><th class="bc-platform-mobile" colspan="7"><span>Mobile</span></th><th class="bc-platform-server" colspan="1"><span>Server</span></th></tr><tr class="bc-browsers"><td></td><th class="bc-browser-chrome"><span class="bc-head-txt-label bc-head-icon-chrome">Chrome</span></th><th class="bc-browser-edge"><span class="bc-head-txt-label bc-head-icon-edge">Edge</span></th><th class="bc-browser-firefox"><span class="bc-head-txt-label bc-head-icon-firefox">Firefox</span></th><th class="bc-browser-ie"><span class="bc-head-txt-label bc-head-icon-ie">Internet Explorer</span></th><th class="bc-browser-opera"><span class="bc-head-txt-label bc-head-icon-opera">Opera</span></th><th class="bc-browser-safari"><span class="bc-head-txt-label bc-head-icon-safari">Safari</span></th><th class="bc-browser-webview_android"><span class="bc-head-txt-label bc-head-icon-webview_android">Android webview</span></th><th class="bc-browser-chrome_android"><span class="bc-head-txt-label bc-head-icon-chrome_android">Chrome for Android</span></th><th class="bc-browser-edge_mobile"><span class="bc-head-txt-label bc-head-icon-edge_mobile">Edge Mobile</span></th><th class="bc-browser-firefox_android"><span class="bc-head-txt-label bc-head-icon-firefox_android">Firefox for Android</span></th><th class="bc-browser-opera_android"><span class="bc-head-txt-label bc-head-icon-opera_android">Opera for Android</span></th><th class="bc-browser-safari_ios"><span class="bc-head-txt-label bc-head-icon-safari_ios">Safari on iOS</span></th><th class="bc-browser-samsunginternet_android"><span class="bc-head-txt-label bc-head-icon-samsunginternet_android">Samsung Internet</span></th><th class="bc-browser-nodejs"><span class="bc-head-txt-label bc-head-icon-nodejs">Node.js</span></th></tr></thead><tbody><tr><th scope="row"><code>function*</code></th><td class="bc-supports-yes bc-browser-chrome"><span class="bc-browser-name">Chrome</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              39</td><td class="bc-supports-yes bc-browser-edge"><span class="bc-browser-name">Edge</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              13</td><td class="bc-supports-yes bc-browser-firefox"><span class="bc-browser-name">Firefox</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              26</td><td class="bc-supports-no bc-browser-ie"><span class="bc-browser-name">IE</span><abbr class="bc-level-no only-icon" title="No support">
<span>No support</span>
</abbr>
              No</td><td class="bc-supports-yes bc-browser-opera"><span class="bc-browser-name">Opera</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              26</td><td class="bc-supports-yes bc-browser-safari"><span class="bc-browser-name">Safari</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              10</td><td class="bc-supports-yes bc-browser-webview_android"><span class="bc-browser-name">WebView Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-chrome_android"><span class="bc-browser-name">Chrome Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              39</td><td class="bc-supports-yes bc-browser-edge_mobile"><span class="bc-browser-name">Edge Mobile</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-firefox_android"><span class="bc-browser-name">Firefox Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              26</td><td class="bc-supports-yes bc-browser-opera_android"><span class="bc-browser-name">Opera Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-safari_ios"><span class="bc-browser-name">Safari iOS</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              10</td><td class="bc-supports-yes bc-browser-samsunginternet_android"><span class="bc-browser-name">Samsung Internet Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              4.0</td><td class="bc-supports-yes bc-browser-nodejs bc-has-history"><span class="bc-browser-name">nodejs</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              4.0.0<div class="bc-icons"></div><section class="bc-history" id="sect1"><dl><dt class="bc-supports-yes bc-supports"><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              4.0.0<div class="bc-icons"></div></dt><dd></dd><dt class="bc-supports-yes bc-supports"><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              0.12<div class="bc-icons"><abbr class="only-icon" title="User must explicitly enable this feature."><span>Disabled</span><i class="ic-disabled"></i></abbr> </div></dt><dd><abbr class="only-icon" title="User must explicitly enable this feature."><span>Disabled</span><i class="ic-disabled"></i></abbr> From version 0.12: this feature is behind the <code>--harmony</code> runtime flag.</dd></dl></section></td></tr><tr><th scope="row"><code>IteratorResult</code> object instead of throwing</th><td class="bc-supports-yes bc-browser-chrome"><span class="bc-browser-name">Chrome</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              49</td><td class="bc-supports-yes bc-browser-edge"><span class="bc-browser-name">Edge</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              13</td><td class="bc-supports-yes bc-browser-firefox"><span class="bc-browser-name">Firefox</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              29</td><td class="bc-supports-no bc-browser-ie"><span class="bc-browser-name">IE</span><abbr class="bc-level-no only-icon" title="No support">
<span>No support</span>
</abbr>
              No</td><td class="bc-supports-yes bc-browser-opera"><span class="bc-browser-name">Opera</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-safari"><span class="bc-browser-name">Safari</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-webview_android"><span class="bc-browser-name">WebView Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-chrome_android"><span class="bc-browser-name">Chrome Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-edge_mobile"><span class="bc-browser-name">Edge Mobile</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-firefox_android"><span class="bc-browser-name">Firefox Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              29</td><td class="bc-supports-yes bc-browser-opera_android"><span class="bc-browser-name">Opera Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-safari_ios"><span class="bc-browser-name">Safari iOS</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-samsunginternet_android"><span class="bc-browser-name">Samsung Internet Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-nodejs"><span class="bc-browser-name">nodejs</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td></tr><tr><th scope="row">Not constructable with <code>new</code> (ES2016)</th><td class="bc-supports-yes bc-browser-chrome"><span class="bc-browser-name">Chrome</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-unknown bc-browser-edge"><span class="bc-browser-name">Edge</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-yes bc-browser-firefox"><span class="bc-browser-name">Firefox</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              43</td><td class="bc-supports-no bc-browser-ie"><span class="bc-browser-name">IE</span><abbr class="bc-level-no only-icon" title="No support">
<span>No support</span>
</abbr>
              No</td><td class="bc-supports-yes bc-browser-opera"><span class="bc-browser-name">Opera</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-safari"><span class="bc-browser-name">Safari</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              10</td><td class="bc-supports-yes bc-browser-webview_android"><span class="bc-browser-name">WebView Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-chrome_android"><span class="bc-browser-name">Chrome Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-unknown bc-browser-edge_mobile"><span class="bc-browser-name">Edge Mobile</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-yes bc-browser-firefox_android"><span class="bc-browser-name">Firefox Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              43</td><td class="bc-supports-yes bc-browser-opera_android"><span class="bc-browser-name">Opera Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-safari_ios"><span class="bc-browser-name">Safari iOS</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              10</td><td class="bc-supports-yes bc-browser-samsunginternet_android"><span class="bc-browser-name">Samsung Internet Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-yes bc-browser-nodejs"><span class="bc-browser-name">nodejs</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td></tr><tr><th scope="row">Trailing comma in parameters</th><td class="bc-supports-unknown bc-browser-chrome"><span class="bc-browser-name">Chrome</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-unknown bc-browser-edge"><span class="bc-browser-name">Edge</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-yes bc-browser-firefox"><span class="bc-browser-name">Firefox</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              52</td><td class="bc-supports-no bc-browser-ie"><span class="bc-browser-name">IE</span><abbr class="bc-level-no only-icon" title="No support">
<span>No support</span>
</abbr>
              No</td><td class="bc-supports-yes bc-browser-opera"><span class="bc-browser-name">Opera</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              Yes</td><td class="bc-supports-unknown bc-browser-safari"><span class="bc-browser-name">Safari</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-unknown bc-browser-webview_android"><span class="bc-browser-name">WebView Android</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-unknown bc-browser-chrome_android"><span class="bc-browser-name">Chrome Android</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-unknown bc-browser-edge_mobile"><span class="bc-browser-name">Edge Mobile</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-yes bc-browser-firefox_android"><span class="bc-browser-name">Firefox Android</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              52</td><td class="bc-supports-unknown bc-browser-opera_android"><span class="bc-browser-name">Opera Android</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-unknown bc-browser-safari_ios"><span class="bc-browser-name">Safari iOS</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-unknown bc-browser-samsunginternet_android"><span class="bc-browser-name">Samsung Internet Android</span><abbr title="Compatibility unknown; please update this.">
                ?
              </abbr></td><td class="bc-supports-yes bc-browser-nodejs"><span class="bc-browser-name">nodejs</span><abbr class="bc-level-yes only-icon" title="Full support">
<span>Full support</span>
</abbr>
              8.0.0</td></tr></tbody></table><section class="bc-legend" id="sect2"><h3 class="offscreen" id="Legend">Legend</h3><dl><dt><span class="bc-supports-yes bc-supports">
<abbr class="bc-level bc-level-yes only-icon" title="Full support">
<span>Full support</span>
                  
                </abbr></span></dt><dd>Full support</dd><dt><span class="bc-supports-no bc-supports">
<abbr class="bc-level bc-level-no only-icon" title="No support">
<span>No support</span>
                  
                </abbr></span></dt><dd>No support</dd><dt><span class="bc-supports-unknown bc-supports">
<abbr class="bc-level bc-level-unknown only-icon" title="Compatibility unknown">
<span>Compatibility unknown</span>
                  
                </abbr></span></dt><dd>Compatibility unknown</dd><dt><abbr class="only-icon" title="User must explicitly enable this feature."><span>User must explicitly enable this feature.</span><i class="ic-disabled"></i></abbr></dt><dd>User must explicitly enable this feature.</dd></dl></section></div> <p></p>
</div>
<h2 id="Firefox浏览器具体事项">Firefox浏览器具体事项</h2>
<h4 id="Firefox_26之前的生成器和迭代器">Firefox 26之前的生成器和迭代器</h4>
<p>旧版本的Firefox实施了旧版本的生成器提案。旧版中用普通的<code>function关键字定义</code>（没有星号）.</p>
<h4 id="IteratorResult不再抛出错误"><code>IteratorResult</code>不再抛出错误</h4>
<p>从Gecko 29 (Firefox 29 / Thunderbird 29 / SeaMonkey 2.26)开始，完成的生成器函数不再抛出<a href="Reference/Global_Objects/TypeError" title="TypeError（类型错误） 对象用来表示值的类型非预期类型时发生的错误。"><code>TypeError</code></a> "generator has already finished". 而是返回一个<code>IteratorResult</code>对象：<span style="font-family: consolas,monaco,andale mono,monospace;">{ value: undefined, done: true }</span> (<a class="external" href="https://bugzilla.mozilla.org/show_bug.cgi?id=958951" rel="noopener" title="FIXED: Return IteratorResult object for completed generators instead of throwing">bug 958951</a>)。</p>
<h2 id="相关链接">相关链接</h2>
<ul>
<li><a href="Reference/Operators/function*" title="function*关键字可以在表达式内部定义一个生成器函数。"><code>function* expression</code></a></li>
<li><a href="Reference/Global_Objects/GeneratorFunction" title="GeneratorFunction构造器生成新的生成器函数 对象。在JavaScript中，生成器函数实际上都是GeneratorFunction的实例对象。"><code>GeneratorFunction</code></a> object</li>
<li><a href="Guide/The_Iterator_protocol">迭代器协议</a></li>
<li><a href="Reference/Operators/yield" title="yield 关键字用来暂停和恢复一个生成器函数（(function* 或遗留的生成器函数）。"><code>yield</code></a></li>
<li><a href="Reference/Operators/yield*" title="yield* 表达式用于委托给另一个generator 或可迭代对象。"><code>yield*</code></a></li>
<li><a href="Reference/Function" title="此页面仍未被本地化, 期待您的翻译!"><code>Function</code></a> object</li>
<li><a href="Reference/Statements/function" title="函数声明定义一个具有指定参数的函数。"><code>function declaration</code></a></li>
<li><a href="Reference/Operators/function" title="function 关键字可以用来在一个表达式中定义一个函数。"><code>function expression</code></a></li>
<li><a href="Reference/Functions_and_function_scope" title="此页面仍未被本地化, 期待您的翻译!"><code>Functions and function scope</code></a></li>
<li>其他网络资源:
  <ul>
<li><a class="external" href="http://facebook.github.io/regenerator/" rel="noopener">Regenerator</a> an ES2015 generator compiler to ES5</li>
<li><a class="external" href="http://www.youtube.com/watch?v=qbKWsbJ76-s" rel="noopener">Forbes Lindesay: Promises and Generators: control flow utopia -- JSConf EU 2013</a></li>
<li><a class="external" href="https://www.youtube.com/watch?v=ZrgEZykBHVo&amp;list=PLuoyIZT5fPlG44bPq50Wgh0INxykdrYX7&amp;index=1" rel="noopener">Hemanth.HM: The New gen of *gen(){}</a></li>
<li><a class="external" href="http://taskjs.org/" rel="noopener">Task.js</a></li>
</ul>
</li>
</ul>
</article>