为JavaScript节点列表转换为阵的最快方法？ [英] Fastest way to convert JavaScript NodeList to Array?

问题描述

previously回答问题，在这里表示，这是最快的方式：

  // NL是一个节点列表
VAR ARR = Array.prototype.slice.call（NL）;
 

在在浏览器上基准我已发现，它是比这个慢的3倍以上：

  VAR ARR = [];
对于（VAR I = 0，N; N = NL [I]; ++ I）arr.push（N）;
 

他们都产生相同的输出，但我觉得很难相信，我的第二个版本是最快的方式，特别是因为人说，否则在这里。

这是在我的浏览器（铬6）一个怪癖？或者是有一个更快的方法？

编辑：对于任何人谁在乎，我定居在以下（这似乎是在每一个我测试浏览器速度最快）：

  // NL是一个节点列表
变种L = []; //将持有节点的数组
对于（VAR I = 0，LL = nl.length;我= 11;！l.push（NL [我++]））;
 

EDIT2：我发现了一个更快的方法

  // NL是节点列表
VAR ARR = [];
对于（VAR I = nl.length;我 - ; arr.unshift（NL [I]））;
 

解决方案

第二项往往是在一些浏览器更快，但主要的一点是，你不得不使用它，因为第一个是不跨浏览器。即使时代他们是，鲍勃迪伦

@kangax （ IE 9 preVIEW 的）

  

Array.prototype.slice 现在可以转换
  某些主机对象（例如节点列表的）
  以阵列 - 这是大多数
  现代浏览器已经能够做到
  相当长一段时间。

例如：

  Array.prototype.slice.call（document.childNodes）;
 

Previously answered questions here said that this was the fastest way:

//nl is a NodeList
var arr = Array.prototype.slice.call(nl);

In benchmarking on my browser I have found that it is more than 3 times slower than this:

var arr = [];
for(var i = 0, n; n = nl[i]; ++i) arr.push(n);

They both produce the same output, but I find it hard to believe that my second version is the fastest possible way, especially since people have said otherwise here.

Is this a quirk in my browser (Chromium 6)? Or is there a faster way?

EDIT: For anyone who cares, I settled on the following (which seems to be the fastest in every browser that I tested):

//nl is a NodeList
var l = []; // Will hold the array of Node's
for(var i = 0, ll = nl.length; i != ll; l.push(nl[i++]));

EDIT2: I found an even faster way

// nl is the nodelist
var arr = [];
for(var i = nl.length; i--; arr.unshift(nl[i]));

解决方案

The second one tends to be faster in some browsers, but the main point is that you have to use it because the first one is just not cross-browser. Even though The Times They Are a-Changin'

@kangax (IE 9 preview)

Array.prototype.slice can now convert certain host objects (e.g. NodeList’s) to arrays — something that majority of modern browsers have been able to do for quite a while.

Example:

Array.prototype.slice.call(document.childNodes);

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