理解lodash中的快速替代apply（） [英] Understanding the fast alternative apply() in lodash

问题描述

我阅读了 lo-dash 的源代码，并找到了函数快速替代 apply（） 此处。

I read the source code of lo-dash, and find there is fast alternative the function apply() here.

  function apply(func, thisArg, args) {
    switch (args.length) {
      case 0: return func.call(thisArg);
      case 1: return func.call(thisArg, args[0]);
      case 2: return func.call(thisArg, args[0], args[1]);
      case 3: return func.call(thisArg, args[0], args[1], args[2]);
    }
    return func.apply(thisArg, args);
  }

我想知道的是实现快速替代功能的真正有效方式应用（）？为什么在这里分解不超过3个args？

I want to know is that really efficient way to implement the fast alternative function apply()? Why there is no more than 3 args to decomposed here?

推荐答案

你需要测试速度差异才能确定。

You would need to bench test speed differences to be sure.

请参阅此SO帖子，了解电话和申请之间的速度差异：

See this SO post on speed differences between call and apply:

Why is call so much faster than apply?

所以这不是一个更快的申请，它只是执行调用，如果它可以。

So it's not really a "faster" apply, it just executes call if it can.

它将需要超过3个参数，最后一行是一个所有调用标准apply的函数。

It will take more than 3 arguments, the last line is a catch all that calls the standard apply.

据推测，_lodash认为有一个巨大的长开关确定传递了多少个参数会使目的失败，并决定将其限制为三个。

Presumably _lodash has considered that having a huge long switch determining how many arguments are passed in defeats the purpose and decided to limit it to three.

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