语法高亮,滚动条美化,设置页面调整

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@@ -4,7 +4,7 @@
<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/promise-all.html" width="100%"></iframe></div>
<p class="hidden">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 <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>
<h2 id="语法">语法</h2>
<pre class="syntaxbox"><var>Promise.all(iterable)</var>;</pre>
<pre><code class="language-javascript"><var>Promise.all(iterable)</var>;</code></pre>
<h3 id="参数">参数</h3>
<dl>
<dt>iterable</dt>
@@ -27,7 +27,7 @@
<h2 id="示例">示例</h2>
<h3 id="Promise.all_的使用"><code>Promise.all</code> 的使用</h3>
<p><code>Promise.all</code> 等待所有都完成(或第一个失败)。</p>
<pre class="brush: js">var p1 = Promise.resolve(3);
<pre><code class="language-javascript">var p1 = Promise.resolve(3);
var p2 = 1337;
var p3 = new Promise((resolve, reject) =&gt; {
setTimeout(resolve, 100, 'foo');
@@ -35,9 +35,9 @@ var p3 = new Promise((resolve, reject) =&gt; {
Promise.all([p1, p2, p3]).then(values =&gt; {
console.log(values); // [3, 1337, "foo"]
});</pre>
});</code></pre>
<p>如果参数中包含非 <code>promise</code> 值,这些值将被忽略,但仍然会被放在返回数组中(如果 <code>promise</code> 完成的话):</p>
<pre class="brush: js">// this will be counted as if the iterable passed is empty, so it gets fulfilled
<pre><code class="language-javascript">// this will be counted as if the iterable passed is empty, so it gets fulfilled
var p = Promise.all([1,2,3]);
// this will be counted as if the iterable passed contains only the resolved promise with value "444", so it gets fulfilled
var p2 = Promise.all([1,2,3, Promise.resolve(444)]);
@@ -54,10 +54,10 @@ setTimeout(function(){
// logs
// Promise { &lt;state&gt;: "fulfilled", &lt;value&gt;: Array[3] }
// Promise { &lt;state&gt;: "fulfilled", &lt;value&gt;: Array[4] }
// Promise { &lt;state&gt;: "rejected", &lt;reason&gt;: 555 }</pre>
// Promise { &lt;state&gt;: "rejected", &lt;reason&gt;: 555 }</code></pre>
<h3 id="Promise.all_的异步和同步"><code>Promise.all</code> 的异步和同步</h3>
<p>下面的例子中演示了 <code>Promise.all</code> 的异步性(如果传入的可迭代对象是空的,就是同步):</p>
<pre class="brush: js">// we are passing as argument an array of promises that are already resolved,
<pre><code class="language-javascript">// we are passing as argument an array of promises that are already resolved,
// to trigger Promise.all as soon as possible
var resolvedPromisesArray = [Promise.resolve(33), Promise.resolve(44)];
@@ -75,9 +75,9 @@ setTimeout(function(){
// Promise { &lt;state&gt;: "pending" }
// the stack is now empty
// Promise { &lt;state&gt;: "fulfilled", &lt;value&gt;: Array[2] }
</pre>
</code></pre>
<p>如果 <code>Promise.all</code> 失败,也是一样的:</p>
<pre class="brush: js">var mixedPromisesArray = [Promise.resolve(33), Promise.reject(44)];
<pre><code class="language-javascript">var mixedPromisesArray = [Promise.resolve(33), Promise.reject(44)];
var p = Promise.all(mixedPromisesArray);
console.log(p);
setTimeout(function(){
@@ -89,9 +89,9 @@ setTimeout(function(){
// Promise { &lt;state&gt;: "pending" }
// the stack is now empty
// Promise { &lt;state&gt;: "rejected", &lt;reason&gt;: 44 }
</pre>
</code></pre>
<p>但是,<code>Promise.all</code> <strong>当且仅当</strong>传入的可迭代对象为空时为同步:</p>
<pre class="brush: js">var p = Promise.all([]); // will be immediately resolved
<pre><code class="language-javascript">var p = Promise.all([]); // will be immediately resolved
var p2 = Promise.all([1337, "hi"]); // non-promise values will be ignored, but the evaluation will be done asynchronously
console.log(p);
console.log(p2)
@@ -105,10 +105,10 @@ setTimeout(function(){
// Promise { &lt;state&gt;: "pending" }
// the stack is now empty
// Promise { &lt;state&gt;: "fulfilled", &lt;value&gt;: Array[2] }
</pre>
</code></pre>
<h3 id="Promise.all_的快速返回失败行为"><code>Promise.all</code> 的快速返回失败行为</h3>
<p><code>Promise.all</code> 在任意一个传入的 <code>promise</code> 失败时返回失败。例如,如果你传入的 <code>promise</code>中,有四个 <code>promise</code> 在一定的时间之后调用成功函数,有一个立即调用失败函数,那么 <code>Promise.all</code> 将立即变为失败。</p>
<pre class="brush: js">var p1 = new Promise((resolve, reject) =&gt; {
<pre><code class="language-javascript">var p1 = new Promise((resolve, reject) =&gt; {
setTimeout(resolve, 1000, 'one');
});
var p2 = new Promise((resolve, reject) =&gt; {
@@ -143,7 +143,7 @@ Promise.all([p1, p2, p3, p4, p5]).then(values =&gt; {
//From console:
//"reject"
</pre>
</code></pre>
<h2 id="技术规范">技术规范</h2>
<table class="standard-table">
<tbody>

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@@ -7,7 +7,7 @@
p.catch(function(reason) {
// 拒绝
});
</pre>
</code></pre>
<h3 id="参数" style="line-height: 24px;">参数</h3>
<dl>
<dt><strong>onRejected</strong></dt>
@@ -24,7 +24,7 @@ p.catch(function(reason) {
<p>Internally calls <code>Promise.prototype.then</code> on the object upon which is called, passing the parameters <code>undefined</code> and the <code>onRejected</code> handler received; then returns the value of that call (which is a <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>).</p>
<h2 id="示例" style="line-height: 30px;">示例</h2>
<h3 id="使用链式语句的_catch方法" style="line-height: 24px;">使用链式语句的 <code>catch</code>方法</h3>
<pre class="brush: js"><code>var p1 = new Promise(function(resolve, reject) {
<pre><code class="language-javascript"><code>var p1 = new Promise(function(resolve, reject) {
resolve('Success');
});</code>
@@ -49,9 +49,9 @@ p1.then(function(value) {
console.log('after a catch the chain is restored');
}, function () {
console.log('Not fired due to the catch');
});</pre>
});</code></pre>
<h3 id="捕获抛出的错误" style="line-height: 30px;">捕获抛出的错误</h3>
<pre class="brush: js"><code>// 抛出一个错误大多数时候将调用catch方法
<pre><code class="language-javascript"><code>// 抛出一个错误大多数时候将调用catch方法
var p1 = new Promise(function(resolve, reject) {
throw 'Uh-oh!';
});
@@ -79,7 +79,7 @@ var p3 = new Promise(function(resolve, reject) {
p3.catch(function(e) {
console.log(e); // 不会执行
});</code></pre>
});</code></code></pre>
<h3 id="如果已决议" style="line-height: 30px;">如果已决议</h3>
<pre><code>//创建一个新的 Promise ,且已决议
var p1 = Promise.resolve("calling next");
@@ -96,7 +96,7 @@ p2.then(function (value) {
}, function (reason) {
console.log("next promise's onRejected");
console.log(reason);
});</code></pre>
});</code></code></pre>
<h2 id="规范" style="line-height: 30px;">规范</h2>
<table class="standard-table">
<tbody>

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@@ -3,11 +3,11 @@
<div> </div>
<div><code><strong>finally()</strong></code> 方法返回一个<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>在promise执行结束时无论结果是fulfilled或者是rejected在执行<a href="Reference/Global_Objects/Promise/then" title="then() 方法返回一个  Promise 。它最多需要有两个参数Promise 的成功和失败情况的回调函数。"><code>then()</code></a><a href="Reference/Global_Objects/Promise/catch" title="catch() 方法返回一个Promise并且处理拒绝的情况。它的行为与调用Promise.prototype.then(undefined, onRejected) 相同。 (事实上, calling obj.catch(onRejected) 内部calls obj.then(undefined, onRejected))."><code>catch()</code></a>后,都会执行<strong><code>finally</code></strong>指定的回调函数。这为指定执行完promise后无论结果是fulfilled还是rejected都需要执行的代码提供了一种方式避免同样的语句需要在<a href="Reference/Global_Objects/Promise/then" title="then() 方法返回一个  Promise 。它最多需要有两个参数Promise 的成功和失败情况的回调函数。"><code>then()</code></a><a href="Reference/Global_Objects/Promise/catch" title="catch() 方法返回一个Promise并且处理拒绝的情况。它的行为与调用Promise.prototype.then(undefined, onRejected) 相同。 (事实上, calling obj.catch(onRejected) 内部calls obj.then(undefined, onRejected))."><code>catch()</code></a>中各写一次的情况。</div>
<h2 id="语法">语法</h2>
<pre class="syntaxbox"><var>p.finally(onFinally)</var>;
<pre><code class="language-javascript"><var>p.finally(onFinally)</var>;
p.finally(function() {
// 返回状态为(resolved 或 rejected)
});参数</pre>
});参数</code></pre>
<dl>
<dt><code>onFinally</code></dt>
<dd><code>Promise</code> 状态改变后执行的回调函数。</dd>
@@ -27,7 +27,7 @@ p.finally(function() {
<p><strong>注意:</strong> 在<code>finally</code>回调中 <code>throw</code>或返回被拒绝的promise将以 <code>throw()</code> 指定的原因拒绝新的promise.</p>
</div>
<h2 id="示例">示例</h2>
<pre class="brush: js">let isLoading = true;
<pre><code class="language-javascript">let isLoading = true;
fetch(myRequest).then(function(response) {
var contentType = response.headers.get("content-type");
@@ -40,7 +40,7 @@ fetch(myRequest).then(function(response) {
.catch(function(error) { console.log(error); })
.finally(function() { isLoading = false; });
</pre>
</code></pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>

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@@ -4,7 +4,7 @@
<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/promise-race.html" width="100%"></iframe></div>
<p class="hidden">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 <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>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre class="syntaxbox"><var>Promise.race(iterable)</var>;</pre>
<pre><code class="language-javascript"><var>Promise.race(iterable)</var>;</code></pre>
<h3 id="参数"><strong>参数</strong></h3>
<dl>
<dt>iterable</dt>
@@ -35,9 +35,9 @@ setTimeout(function(){
// logs, in order:
// Promise { &lt;state&gt;: "pending" }
// the stack is now empty
// Promise { &lt;state&gt;: "fulfilled", &lt;value&gt;: 33 }</code></pre>
// Promise { &lt;state&gt;: "fulfilled", &lt;value&gt;: 33 }</code></code></pre>
<h3 id="使用_Promise.race__setTimeout_的示例"><code><font face="Open Sans, sans-serif">使用 </font>Promise.race</code>  <code>setTimeout 的示例</code></h3>
<pre class="brush: js">var p1 = new Promise(function(resolve, reject) {
<pre><code class="language-javascript">var p1 = new Promise(function(resolve, reject) {
setTimeout(resolve, 500, "one");
});
var p2 = new Promise(function(resolve, reject) {
@@ -76,7 +76,7 @@ Promise.race([p5, p6]).then(function(value) {
console.log(reason); // "six"
// p6 更快,所以它失败了
});
</pre>
</code></pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>

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@@ -3,7 +3,7 @@
<h2 id="Summary" name="Summary">概述</h2>
<p><code><strong>Promise.reject(reason)</strong></code>方法返回一个带有拒绝原因reason参数的Promise对象。</p>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre class="syntaxbox"><var>Promise.reject(reason)</var>;</pre>
<pre><code class="language-javascript"><var>Promise.reject(reason)</var>;</code></pre>
<h3 id="Parameters">Parameters</h3>
<dl>
<dt>reason</dt>
@@ -17,7 +17,7 @@
<p><font face="Open Sans, sans-serif">静态函数</font><code>Promise.reject</code>返回一个被拒绝的<code>Promise对象</code>。通过使用<a href="Reference/Global_Objects/Error" title="通过Error的构造器可以创建一个错误对象。当运行时错误产生时Error的实例对象会被抛出。Error对象也可用于用户自定义的异常的基础对象。下面列出了各种内建的标准错误类型。"><code>Error</code></a>的实例获取错误原因<code>reason</code>对调试和选择性错误捕捉很有帮助。</p>
<h2 id="示例">示例</h2>
<h3 id="使用静态Promise.reject()方法">使用静态<code>Promise.reject()</code>方法</h3>
<pre class="brush: js">Promise.reject("Testing static reject").then(function(reason) {
<pre><code class="language-javascript">Promise.reject("Testing static reject").then(function(reason) {
// 未被调用
}, function(reason) {
console.log(reason); // "Testing static reject"
@@ -27,7 +27,7 @@ Promise.reject(new Error("fail")).then(function(result) {
// 未被调用
}, function(error) {
console.log(error); // stacktrace
});</pre>
});</code></pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>

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@@ -5,9 +5,9 @@
<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/promise-resolve.html" width="100%"></iframe></div>
<p class="hidden">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 <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>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre class="syntaxbox"><var>Promise.resolve(value)</var>;
<pre><code class="language-javascript"><var>Promise.resolve(value)</var>;
Promise.resolve(promise);
Promise.resolve(thenable);</pre>
Promise.resolve(thenable);</code></pre>
<h3 id="参数">参数</h3>
<dl>
<dt>value</dt>
@@ -21,20 +21,20 @@ Promise.resolve(thenable);</pre>
<p>静态方法 <code>Promise.resolve</code>返回一个解析过的<code>Promise</code>对象.</p>
<h2 id="示例">示例</h2>
<h3 id="使用静态方法Promise.resolve">使用静态方法<code>Promise.resolve</code></h3>
<pre class="brush: js">Promise.resolve("Success").then(function(value) {
<pre><code class="language-javascript">Promise.resolve("Success").then(function(value) {
console.log(value); // "Success"
}, function(value) {
// 不会被调用
});
</pre>
</code></pre>
<h3 id="对一个数组进行resolve">对一个数组进行resolve</h3>
<pre class="brush: js">var p = Promise.resolve([1,2,3]);
<pre><code class="language-javascript">var p = Promise.resolve([1,2,3]);
p.then(function(v) {
console.log(v[0]); // 1
});
</pre>
</code></pre>
<h3 id="Resolve另一个promise对象">Resolve另一个promise对象</h3>
<pre class="brush: js">var original = Promise.resolve('我在第二行');
<pre><code class="language-javascript">var original = Promise.resolve('我在第二行');
var cast = Promise.resolve(original);
cast.then(function(value) {
console.log('value: ' + value);
@@ -45,9 +45,9 @@ console.log('original === cast ? ' + (original === cast));
* 打印顺序如下,这里有一个同步异步先后执行的区别
* original === cast ? true
* value: 我在第二行
*/</pre>
*/</code></pre>
<h3 id="resolve_thenable的对象们并抛出错误">resolve thenable的对象们并抛出错误</h3>
<pre class="brush: js">// Resolve一个thenable对象
<pre><code class="language-javascript">// Resolve一个thenable对象
var p1 = Promise.resolve({
then: function(onFulfill, onReject) { onFulfill("fulfilled!"); }
});
@@ -86,7 +86,7 @@ p3.then(function(v) {
}, function(e) {
// 不会被调用
});
</pre>
</code></pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>

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@@ -7,14 +7,14 @@
<p>注意:如果忽略针对某个状态的回调函数参数,或者提供非函数 (nonfunction) 参数,那么 <code>then</code> 方法将会丢失关于该状态的回调函数信息,但是并不会产生错误。如果调用 <code>then</code><code>Promise</code> 的状态fulfillment 或 rejection发生改变但是 <code>then</code> 中并没有关于这种状态的回调函数,那么 <code>then</code> 将创建一个没有经过回调函数处理的新 <code>Promise</code> 对象,这个新 <code>Promise</code> 只是简单地接受调用这个 <code>then</code> 的原 <code>Promise</code> 的终态作为它的终态。</p>
</div>
<h2 id="Syntax" name="Syntax">语法</h2>
<pre class="syntaxbox"><var>p.then(onFulfilled, onRejected)</var>;
<pre><code class="language-javascript"><var>p.then(onFulfilled, onRejected)</var>;
p.then(function(value) {
// fulfillment
}, function(reason) {
// rejection
});
</pre>
</code></pre>
<h3 id="参数">参数</h3>
<dl>
<dt>onFulfilled</dt>
@@ -30,7 +30,7 @@ p.then(function(value) {
// 'bar' 不是函数,会在内部被替换为 (x) =&gt; x
p.then('bar').then((value) =&gt; {
console.log(value) // 'foo'
})</pre>
})</code></pre>
<p> </p>
<dl>
<dt>
@@ -50,7 +50,7 @@ p.then('bar').then((value) =&gt; {
<p>由于 <code>then</code> 和 <a href="Reference/Global_Objects/Promise/catch" title="catch() 方法返回一个Promise并且处理拒绝的情况。它的行为与调用Promise.prototype.then(undefined, onRejected) 相同。 (事实上, calling obj.catch(onRejected) 内部calls obj.then(undefined, onRejected))."><code>Promise.prototype.catch()</code></a> 方法都会返回 promise它们可以被链式调用 — 一种称为<strong>复合</strong> <em>composition </em>的操作.</p>
<h2 id="示例">示例</h2>
<h3 id="使用then方法"><code><font face="Open Sans, sans-serif">使用</font>then方法</code></h3>
<pre class="brush: js">let p1 = new Promise(function(resolve, reject) {
<pre><code class="language-javascript">let p1 = new Promise(function(resolve, reject) {
resolve("Success!");
// or
// reject ("Error!");
@@ -61,11 +61,11 @@ p1.then(function(value) {
}, function(reason) {
console.log(reason); // Error!
});
</pre>
</code></pre>
<h3 id="链式调用">链式调用</h3>
<p><font face="Open Sans, sans-serif">then 方法返回</font>一个Promise 对象其允许方法链。</p>
<p>你可以传递一个 lambda 给 then 并且如果它返回一个 promise一个等价的 Promise 将暴露给后续的方法链。下面的代码片段使用 setTimout 函数来模拟异步代码操作。</p>
<pre class="brush: js">Promise.resolve("foo")
<pre><code class="language-javascript">Promise.resolve("foo")
// 1. 接收 "foo" 并与 "bar" 拼接并将其结果做为下一个resolve返回。
.then(function(string) {
return new Promise(function(resolve, reject) {
@@ -94,9 +94,9 @@ p1.then(function(value) {
// 注意 `string` 这时不会存在 'baz'。
// 因为这是发生在我们通过setTimeout模拟的异步函数中。
console.log(string);
});</pre>
});</code></pre>
<p>当一个值只是从一个 lambda 内部返回时,它将有效地返回 Promise.resolve&lt;由被调用的处理程序返回的值&gt;)。</p>
<pre class="brush: js">var p2 = new Promise(function(resolve, reject) {
<pre><code class="language-javascript">var p2 = new Promise(function(resolve, reject) {
resolve(1);
});
@@ -109,9 +109,9 @@ p2.then(function(value) {
p2.then(function(value) {
console.log(value); // 1
});</pre>
});</code></pre>
<p>如果函数抛出错误或返回一个拒绝的Promise则调用将返回一个拒绝的Promise。</p>
<pre class="brush: js">Promise.resolve()
<pre><code class="language-javascript">Promise.resolve()
.then( () =&gt; {
// 使 .then() 返回一个 rejected promise
throw 'Oh no!';
@@ -120,13 +120,13 @@ p2.then(function(value) {
console.log( 'Not called.' );
}, reason =&gt; {
console.error( 'onRejected function called: ', reason );
});</pre>
});</code></pre>
<p>在其他情况下,一个 resolving Promise 会被返回。在下面的例子里,第一个 then() 会返回一个用 resolving Promise 包装的 42即使之前的 Promise 是 rejected 的。</p>
<pre class="brush: js">Promise.reject()
<pre><code class="language-javascript">Promise.reject()
  .then( () =&gt; 99, () =&gt; 42 ) // onRejected returns 42 which is wrapped in a resolving Promise
  .then( solution =&gt; console.log( 'Resolved with ' + solution ) ); // Resolved with 42</pre>
  .then( solution =&gt; console.log( 'Resolved with ' + solution ) ); // Resolved with 42</code></pre>
<p>实际上,捕获 rejected promise 的需求经常大于使用 then 的两种情况语法,比如下面这样的:</p>
<pre class="brush: js">Promise.resolve()
<pre><code class="language-javascript">Promise.resolve()
.then( () =&gt; {
// 使 .then() 返回一个 rejected promise
throw 'Oh no!';
@@ -136,9 +136,9 @@ p2.then(function(value) {
})
.then( () =&gt; {
console.log( "I am always called even if the prior then's promise rejects" );
});</pre>
});</code></pre>
<p>你也可以在另一个顶层函数上使用链式去实现带有 Promise-based API 的函数。</p>
<pre class="brush: js">function fetch_current_data() {
<pre><code class="language-javascript">function fetch_current_data() {
// fetch() API 返回了一个 Promise.
// 这个函数提供了类似的API
// 这个函数除了实现 Promise它还能够完成更多的工作。
@@ -151,9 +151,9 @@ p2.then(function(value) {
return j; // fulfillment value given to user of
// fetch_current_data().then()
});
}</pre>
}</code></pre>
<p>如果 <code>onFulfilled</code> 返回了一个 promise<code>then</code> 的返回值就会被 Promise resolved或者rejected。</p>
<pre class="brush: js">function resolveLater(resolve, reject) {
<pre><code class="language-javascript">function resolveLater(resolve, reject) {
setTimeout(function () {
resolve(10);
}, 1000);
@@ -185,7 +185,7 @@ p3.then(function(v) {
console.log('resolved', v);
}, function(e) {
console.log('rejected', e); // "rejected", 20
});</pre>
});</code></pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>