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docs/javascript/Reference/Functions/Rest_parameters.html
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@@ -4,10 +4,10 @@
<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/functions-restparameters.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>
<h2 id="语法">语法</h2>
<pre class="brush: js">function(a, b, ...theArgs) {
<pre><code class="language-javascript">function(a, b, ...theArgs) {
// ...
}
</pre>
</code></pre>
<h2 id="描述">描述</h2>
<p>如果函数的最后一个命名参数以<code>...</code>为前缀，则它将成为一个由剩余参数组成的真数组，其中从<code>0</code>（包括）到<code>theArgs.length</code>（排除）的元素由传递给函数的实际参数提供。</p>
<p>在上面的例子中，<code>theArgs</code>将收集该函数的第三个参数（因为第一个参数被映射到<code>a</code>，而第二个参数映射到<code>b</code>）和所有后续参数。</p>
@@ -40,27 +40,27 @@ function f(a, b) {
function f(...args) {
var normalArray = args;
var first = normalArray.shift(); // OK, gives the first argument
}</code></pre>
}</code></code></pre>
<h3 id="解构剩余参数">解构剩余参数</h3>
<p>剩余参数可以被解构，这意味着他们的数据可以被解包到不同的变量中。请参阅<a href="Reference/Operators/Destructuring_assignment">解构赋值</a>。</p>
<pre class="brush: js">function f(...[a, b, c]) {
<pre><code class="language-javascript">function f(...[a, b, c]) {
return a + b + c;
}
f(1) // NaN (b and c are undefined)
f(1, 2, 3) // 6
f(1, 2, 3, 4) // 6 (the fourth parameter is not destructured)</pre>
f(1, 2, 3, 4) // 6 (the fourth parameter is not destructured)</code></pre>
<h2 id="Example" name="Example">示例</h2>
<p>因为<code>theArgs</code>是个数组，所以你可以使用<code>length</code>属性得到剩余参数的个数：</p>
<pre class="brush: js">function fun1(...theArgs) {
<pre><code class="language-javascript">function fun1(...theArgs) {
  alert(theArgs.length);
}
 
fun1();  // 弹出 "0", 因为theArgs没有元素
fun1(5); // 弹出 "1", 因为theArgs只有一个元素
fun1(5, 6, 7); // 弹出 "3", 因为theArgs有三个元素</pre>
fun1(5, 6, 7); // 弹出 "3", 因为theArgs有三个元素</code></pre>
<p>下例中，剩余参数包含了从第二个到最后的所有实参，然后用第一个实参依次乘以它们：</p>
<pre class="brush: js">function multiply(multiplier, ...theArgs) {
<pre><code class="language-javascript">function multiply(multiplier, ...theArgs) {
return theArgs.map(function (element) {
return multiplier * element;
});
@@ -68,9 +68,9 @@ fun1(5, 6, 7); // 弹出 "3", 因为theArgs有三个元素</pre>
var arr = multiply(2, 1, 2, 3);
console.log(arr); // [2, 4, 6]
</pre>
</code></pre>
<p>下例演示了你可以在剩余参数上使用任意的数组方法，而<code>arguments</code>对象不可以：</p>
<pre class="brush: js">function sortRestArgs(...theArgs) {
<pre><code class="language-javascript">function sortRestArgs(...theArgs) {
  var sortedArgs = theArgs.sort();
  return sortedArgs;
}
@@ -83,14 +83,14 @@ function sortArguments() {
}
 
alert(sortArguments(5,3,7,1)); // 抛出TypeError异常:arguments.sort is not a function
</pre>
</code></pre>
<p>为了在<code>arguments</code>对象上使用<code>Array</code>方法，它必须首先被转换为一个真正的数组。</p>
<pre class="brush: js">function sortArguments() {
<pre><code class="language-javascript">function sortArguments() {
var args = Array.prototype.slice.call(arguments);
var sortedArgs = args.sort();
return sortedArgs;
}
console.log(sortArguments(5, 3, 7, 1)); // shows 1, 3, 5, 7</pre>
console.log(sortArguments(5, 3, 7, 1)); // shows 1, 3, 5, 7</code></pre>
<h2 id="Specifications" name="Specifications">规范</h2>
<table class="standard-table">
<tbody>