我应该在局部变量中引用'this'吗？ [英] Should I reference 'this' in local variable?

问题描述

我经常在代码中看到这一点： var me = this; 。这是为什么？如果我在局部变量中引用'this'，会有一些性能上的提升吗？

I often see this in code: var me = this;. Why is that? Is there some performance gain if I reference 'this' in local variable?

推荐答案

如果里面有函数，这很有用一个函数，这些嵌套函数中的代码需要从外部上下文中访问 this 的值。

It's useful if there are functions inside a function, such that code in those nested functions needs access to the value of this from the outer context.

function example() {
  var me = this;
  document.getElementById('whatever').onclick = function() {
    me.clicked = 1;
  };
}

因为这个是为每个函数调用重新建立，而不是在变量中隐藏外部这个，根本无法从内部函数引用它。

Because this is established anew for every function call, without stashing the outer this in a variable there'd be no way to reference it at all from the inner function.

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