study/uTools-Manuals
1
0
Fork 0
mirror of https://github.com/fofolee/uTools-Manuals.git synced 2025-12-15 07:06:53 +08:00
Code Issues Packages Projects Releases Wiki Activity

语法高亮，滚动条美化，设置页面调整

Browse Source
This commit is contained in:
fofolee
2019-04-19 02:41:09 +08:00
parent 1e8f76c000
commit 359d29ee0b
1590 changed files with 12328 additions and 11441 deletions
Download Patch File Download Diff File Expand all files Collapse all files

16
docs/javascript/Reference/Statements/async_function.html
View File

@@ -7,8 +7,8 @@
<div><iframe class="interactive interactive-js taller" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/statement-async.html" width="100%"></iframe></div>
<p class="hidden">该交互式demo源文件存储于Github仓库中。如果希望为此交互式项目做出贡献,请 clone <a class="external" href="https://github.com/mdn/interactive-examples" rel="noopener">https://github.com/mdn/interactive-examples</a> 项目并用pull形式向我们的原始仓库发出请求。</p>
<h2 id="语法">语法</h2>
<pre class="syntaxbox">async function <em>name</em>([<em>param</em>[, <em>param</em>[, ... <em>param</em>]]]) { <em>statements </em>}
</pre>
<pre><code class="language-javascript">async function <em>name</em>([<em>param</em>[, <em>param</em>[, ... <em>param</em>]]]) { <em>statements </em>}
</code></pre>
<h3 id="参数">参数</h3>
<dl>
<dt><code>name</code></dt>
@@ -35,7 +35,7 @@
</div>
<h2 id="示例">示例</h2>
<h3 id="简单例子">简单例子</h3>
<pre class="brush: js">var resolveAfter2Seconds = function() {
<pre><code class="language-javascript">var resolveAfter2Seconds = function() {
  console.log("starting slow promise");
  return new Promise(resolve =&gt; {
    setTimeout(function() {
@@ -114,7 +114,7 @@ setTimeout(parallel, 10000); // truly parallel: after 1 second, logs "fast", the
// wait again
setTimeout(parallelPromise, 13000); // same as parallel
</pre>
</code></pre>
<div class="note">
<h4 id="await_and_parallelism"><code>await</code> and parallelism</h4>
<p>在<code>sequentialStart</code>中，程序在第一个<code>await</code>停留了2秒，然后又在第二个<code>await</code>停留了1秒。直到第一个计时器结束后，第二个计时器才被创建。程序是3秒后才结束。</p>
@@ -136,7 +136,7 @@ setTimeout(parallelPromise, 13000); // same as parallel
</div>
<h3 id="通过async函数重写_promise_链">通过<code>async</code>函数重写 promise 链</h3>
<p>返回 <a href="Reference/Global_Objects/Promise" title="Promise 对象用于表示一个异步操作的最终状态（完成或失败），以及该异步操作的结果值。"><code>Promise</code></a>的 API 将会被用于 promise 链，它会将函数分成若干部分。例如下面代码：</p>
<pre class="brush: js">function getProcessedData(url) {
<pre><code class="language-javascript">function getProcessedData(url) {
return downloadData(url) // 返回一个 promise 对象
.catch(e =&gt; {
return downloadFallbackData(url) // 返回一个 promise 对象
@@ -144,9 +144,9 @@ setTimeout(parallelPromise, 13000); // same as parallel
.then(v =&gt; {
return processDataInWorker(v); // 返回一个 promise 对象
});
}</pre>
}</code></pre>
<p>可以通过如下所示的一个<code>async</code>函数重写：</p>
<pre class="brush: js">async function getProcessedData(url) {
<pre><code class="language-javascript">async function getProcessedData(url) {
let v;
try {
v = await downloadData(url);
@@ -155,7 +155,7 @@ setTimeout(parallelPromise, 13000); // same as parallel
}
return processDataInWorker(v);
}
</pre>
</code></pre>
<p>注意，在上述示例中，<code>return</code> 语句中没有 <code>await</code> 操作符，因为 <code>async function</code> 的返回值将被隐式地传递给 <code><a href="Reference/Global_Objects/Promise/resolve" title="The source for this interactive demo is stored in a GitHub repository. If you'd like to contribute to the interactive demo project, please clone https://github.com/mdn/interactive-examples and send us a pull request."><code>Promise.resolve</code></a></code>。</p>
<h2 id="规范">规范</h2>
<table class="standard-table">