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] }

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] }

在使用大多数现代浏览器执行此测试后: https://jsben.ch/wY5fo

目前，最快的循环形式(在我看来也是语法上最明显的)。

具有长度缓存的标准for循环

    var i = 0, len = myArray.length;
    while (i < len) {
        // your code
        i++
    }

我想说，这绝对是我为JavaScript引擎开发者喝彩的地方。运行时应该优化为清晰，而不是聪明。

var arr = []; // The array
var i = 0;
while (i < arr.length) {
    // Do something with arr[i]
    i++;
}

i++比++ I，——I和I——快

此外，您可以保存最后一次需要访问i时执行arr[i++]的最后一行(但这可能很难调试)。

您可以在这里(使用其他循环测试)测试它:http://jsperf.com/for-vs-whilepop/5

最快的方法是传统的for循环。这里有一个更全面的性能比较。

https://gists.cwidanage.com/2019/11/how-to-iterate-over-javascript-arrays.html

另一个jsperf.com测试:http://jsperf.com/while-reverse-vs-for-cached-length

反向while循环似乎是最快的。唯一的问题是while(——i)将停止于0。我怎么能访问数组[0]在我的循环那么?