截至2017年9月，这些jsperf测试显示以下模式在Chrome 60上性能最佳:

function foo(x) {
 x;
};
arr.forEach(foo);

有人能繁殖吗?

现在是2017年。

我做了一些测试

https://jsperf.com/fastest-way-to-iterate-through-an-array/

看起来while方法在Chrome上是最快的。

看起来左边递减(——i)比Firefox上的其他递减(++i, i——，i++)快得多。

这种方法平均来说是最快的。但是它以相反的顺序迭代数组。

let i = array.length;
while (--i >= 0) {
    doSomething(array[i]);
}

如果前向顺序很重要，可以使用这种方法。

let ii = array.length;
let i = 0;
while (i < ii) {
    doSomething(array[i]);
    ++i;
}

如果您想要一个更快的for循环，请在循环之外定义变量并使用下面的语法

  const iMax = lengthOftheLoop;
  var i = 0;
  for (; i < iMax; i++) {
    console.log("loop"+i);
  }

参考:https://medium.com/kbdev/voyage - - -最有效循环- - nodejs和位- js - 5961 d4524c2e

截至2016年6月，在最新的Chrome上做了一些测试(2016年5月，浏览器市场份额为71%，并且还在增加):

The fastest loop is a for loop, both with and without caching length delivering really similar performance. (The for loop with cached length sometimes delivered better results than the one without caching, but the difference is almost negligible, which means the engine might be already optimized to favor the standard and probably most straightforward for loop without caching). The while loop with decrements was approximately 1.5 times slower than the for loop. A loop using a callback function (like the standard forEach), was approximately 10 times slower than the for loop.

我相信这个线程太旧了，它误导程序员认为他们需要缓存长度，或者使用反向遍历，同时递减来获得更好的性能，编写的代码不太容易读懂，更容易出错，而不是简单直接的for循环。因此，我建议:

If your app iterates over a lot of items or your loop code is inside a function that is used often, a straightforward for loop is the answer: for (var i = 0; i < arr.length; i++) { // Do stuff with arr[i] or i } If your app doesn't really iterate through lots of items or you just need to do small iterations here and there, using the standard forEach callback or any similar function from your JS library of choice might be more understandable and less prone to errors, since index variable scope is closed and you don't need to use brackets, accessing the array value directly: arr.forEach(function(value, index) { // Do stuff with value or index }); If you really need to scratch a few milliseconds while iterating over billions of rows and the length of your array doesn't change through the process, you might consider caching the length in your for loop. Although I think this is really not necessary nowadays: for (var i = 0, len = arr.length; i < len; i++) { // Do stuff with arr[i] }

我总是用第一种体裁写作。

即使编译器足够智能，可以为数组优化它，但如果我们在这里使用DOMNodeList或一些计算长度的复杂对象，它仍然是智能的?

我知道关于数组的问题是什么，但我认为用一种风格编写所有循环是一个很好的实践。

循环javascript数组的最快方法是:

var len = arr.length;
while (len--) {
    // blah blah
}

请看这篇文章的完整比较