什么是“这个”请参考ES6中的箭头功能？ [英] What does "this" refer to in arrow functions in ES6?

问题描述

我在几个地方阅读过，主要区别是这个在箭头函数中是词法绑定的。这很好，但我实际上并不知道这是什么意思。

我知道这意味着它在定义功能体的大括号的范围内是独一无二的，但是我实际上不能告诉你以下代码的输出，因为我不知道这个是什么指向的，除非它指的是胖箭头函数本身...这似乎没有用。

  var testFunction =（）=> {console.log（this）}; 
 testFunction（）; 
  

解决方案

箭头函数捕获封闭上下文的此值

  function Person（）{
 this.age = 0; 
 
 setInterval（（）=> {
 this.age ++; // | this |正确地指人物对象
}，1000）; 
} 
 
 var p = new Person（）; 
  

所以，直接回答你的问题，这个在你的箭头函数内部将具有与分配箭头函数之前相同的值。

I've read in several places that the key difference is that "this is lexically bound in arrow functions." That's all well and good, but I don't actually know what that means.

I know it means it's unique within the confines of the braces defining the function's body, but I couldn't actually tell you the output of the following code, because I have no idea what this is referring to, unless it's referring to the fat arrow function itself....which doesn't seem useful.

var testFunction = () => { console.log(this) };
testFunction();

解决方案

Arrow functions capture the this value of the enclosing context

function Person(){
  this.age = 0;

  setInterval(() => {
    this.age++; // |this| properly refers to the person object
  }, 1000);
}

var p = new Person();

So, to directly answer your question, this inside your arrow function would have the same value as it did right before the arrow function was assigned.

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