在JavaScript中循环数组的最快方法是什么？ [英] What's the fastest way to loop through an array in JavaScript?

问题描述

我从书中了解到你应该写这样的循环：

I learned from books that you should write for loop like this：

for(var i=0, len=arr.length; i < len; i++){
    // blah blah
}

所以每次都不会计算 arr.length 。

so the arr.length will not be calculated each time.

其他人说编译器会对此做一些优化，所以你可以写：

Others say that the compiler will do some optimization to this, so you can just write:

for(var i=0; i < arr.length; i++){
    // blah blah
}

我只是想知道哪种方式最好？

I just want to know which is the best way in practice?

推荐答案

用大多数现代浏览器执行此测试后......

After performing this test with most modern browsers...

http://jsben.ch/y3SpC

目前 ，最快的循环形式（在我看来，语法最明显）。

Currently, the fastest form of loop (and in my opinion the most syntactically obvious).

标准具有长度缓存的循环

a standard for loop with length caching

for (var i = 0, len = myArray.length; i < len; i++) {

}

我想这肯定是我鼓掌JavaScript引擎的情况开发人员。运行时间应针对清晰度进行优化，不要聪明。

I would say this is definitely a case where I applaud JavaScript engine developers. A run time should be optimized for clarity, not cleverness.

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