study/uTools-Manuals
1
0
Fork 0
mirror of https://github.com/fofolee/uTools-Manuals.git synced 2025-12-16 07:51:52 +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

32
docs/javascript/Reference/Global_Objects/Array/from.html
View File

@@ -4,8 +4,8 @@
<div><iframe class="interactive interactive-js" frameborder="0" height="250" src="https://interactive-examples.mdn.mozilla.net/pages/js/array-from.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="Syntax" name="Syntax">语法</h2>
<pre class="syntaxbox"><code>Array.from(arrayLike[, mapFn[, thisArg]])
</code></pre>
<pre><code class="language-javascript"><code>Array.from(arrayLike[, mapFn[, thisArg]])
</code></code></pre>
<h3 id="Parameters" name="Parameters">参数</h3>
<dl>
<dt><code>arrayLike</code></dt>
@@ -28,28 +28,28 @@
<p>在 ES2015 中， <code>Class</code> 语法允许我们为内置类型（比如 <code>Array</code>）和自定义类新建子类（比如叫 <code>SubArray</code>）。这些子类也会继承父类的静态方法，比如 <code>SubArray.from()</code>，调用该方法后会返回子类 <code>SubArray</code> 的一个实例，而不是 <code>Array</code> 的实例。</p>
<h2 id="示例">示例</h2>
<h3 id="Array_from_a_String">Array from a <code>String</code></h3>
<pre class="brush: js">Array.from('foo');
// ["f", "o", "o"]</pre>
<pre><code class="language-javascript">Array.from('foo');
// ["f", "o", "o"]</code></pre>
<h3 id="Array_from_a_Set">Array from a <code>Set</code></h3>
<pre class="brush: js">let s = new Set(['foo', window]);
<pre><code class="language-javascript">let s = new Set(['foo', window]);
Array.from(s);
// ["foo", window]
</pre>
</code></pre>
<h3 id="Array_from_a_Map">Array from a <code>Map</code></h3>
<pre class="brush: js">let m = new Map([[1, 2], [2, 4], [4, 8]]);
<pre><code class="language-javascript">let m = new Map([[1, 2], [2, 4], [4, 8]]);
Array.from(m);
// [[1, 2], [2, 4], [4, 8]]
</pre>
</code></pre>
<h3 id="Array_from_an_Array-like_object_(arguments)">Array from an Array-like object (arguments)</h3>
<pre class="brush: js">function f() {
<pre><code class="language-javascript">function f() {
return Array.from(arguments);
}
f(1, 2, 3);
// [1, 2, 3]</pre>
// [1, 2, 3]</code></pre>
<h3 id="在Array.from中使用箭头函数">在<code>Array.from</code>中使用箭头函数</h3>
<pre class="brush: js">// Using an arrow function as the map function to
<pre><code class="language-javascript">// Using an arrow function as the map function to
// manipulate the elements
Array.from([1, 2, 3], x =&gt; x + x);
// x =&gt; x + x代表这是一个函数，只是省略了其他的定义，这是一种Lambda表达式的写法
@@ -62,18 +62,18 @@ Array.from([1, 2, 3], x =&gt; x + x);
// the value of `v` below will be `undefined`
Array.from({length: 5}, (v, i) =&gt; i);
// [0, 1, 2, 3, 4]
</pre>
</code></pre>
<h3 id="数组去重合并">数组去重合并</h3>
<pre class="brush: js">function combine(){
<pre><code class="language-javascript">function combine(){
let arr = [].concat.apply([], arguments); //没有去重复的新数组
return Array.from(new Set(arr));
}
var m = [1, 2, 2], n = [2,3,3];
console.log(combine(m,n)); // [1, 2, 3]</pre>
console.log(combine(m,n)); // [1, 2, 3]</code></pre>
<h2 id="Polyfill">Polyfill</h2>
<p>ECMA-262 第六版标准添加了<code> Array.from </code>。有些实现中可能尚未包括在其中。你可以通过在脚本前添加如下内容作为替代方法，以使用未原生支持的 <code>Array.from</code> 方法。该算法按照  ECMA-262 第六版中的规范实现，并假定 <code>Object</code> 和 <code>TypeError</code> 有其本身的值，  <code>callback.call</code> 对应 <a href="Reference/Global_Objects/Function/call" title="call() 方法调用一个函数, 其具有一个指定的this值和分别地提供的参数(参数的列表)。"><code>Function.prototype.call</code></a> 。此外，鉴于无法使用 Polyfill 实现真正的的迭代器，该实现不支持规范中定义的泛型可迭代元素。</p>
<pre class="brush: js">// Production steps of ECMA-262, Edition 6, 22.1.2.1
<pre><code class="language-javascript">// Production steps of ECMA-262, Edition 6, 22.1.2.1
// Reference: https://people.mozilla.org/~jorendorff/es6-draft.html#sec-array.from
if (!Array.from) {
Array.from = (function () {
@@ -165,7 +165,7 @@ if (!Array.from) {
};
}());
}
</pre>
</code></pre>
<h2 id="规范">规范</h2>
<table class="standard-table">
<tbody>