javascript自定义范围绑定功能 [英] javascript custom scope binding function

问题描述

我正在阅读本文- http://www.robertsosinski.com/2009/04/28/binding-scope-in​​-javascript/ -创建自定义绑定函数的地方.

I am reading this article - http://www.robertsosinski.com/2009/04/28/binding-scope-in-javascript/ - where a custom bind function is made.

Function.prototype.bind = function(scope) {
  var _function = this;

  return function() {
    return _function.apply(scope, arguments);
  }
}

alice = {
  name: "alice"
}

eve = {
  talk: function(greeting) {
    console.log(greeting + ", my name is " + this.name);
  }.bind(alice) // <- bound to "alice"
}

eve.talk("hello");
// hello, my name is alice

我的问题是这条线特别是

My question is this line in particlar

 return function() {
    return _function.apply(scope, arguments);
  }

为什么在_function.apply(作用域，参数)中返回；那里?它在做什么以及正在返回什么?我删除了该退货，但仍然有效.

Why is the return in _function.apply(scope, arguments); there? And what is it doing and what is being returned? I removed that return and it still works.

推荐答案

Why is the return in _function.apply(scope, arguments); there? And what is it doing and what is being returned? I removed that return and it still works. 

这是您要返回值的地方.当前，您的talk函数没有返回任何值，因此您不需要它.如果您将通话功能更改为

This is there in case you want to return a value. Currently your talk function is not returning any value so you don't need it. if you change your talk function to

eve = {
  talk: function(greeting) {
    return ( greeting + ", my name is " + this.name) ;
  }.bind(alice) // <- bound to "alice"
}

console.log(eve.talk("hello"));

现在您将了解为什么需要退货

Now you will realize why return is required

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