“调用/应用"和“绑定"有什么区别 [英] what's the difference between 'call/apply' and 'bind'

问题描述

var obj = {x: 81,getX:函数(){控制台.log(this.x)}};var getX = obj.getX.bind(obj);//使用obj作为'this';getX();//81var getX = 函数(){obj.getX.apply(obj);}getX();//也是81

bind和call/apply的用法看起来很像，我想知道它们有什么区别.上面两个getX函数是一样的吗?

解决方案

bind 返回一个函数，该函数的行为与原始函数类似，但预定义了 this.当您想将函数传递给事件处理程序或其他异步回调时，通常会使用它.

call 和 apply 将立即调用一个函数，让您指定 this 的值以及该函数将接收的任何参数.

您的第二个示例定义了一个调用 apply 的匿名函数.这是一种常见的模式；bind 提供了一个标准实现，它允许您通过一个简单的函数调用来完成它(因此编写起来更快更容易).

var obj = {
   x: 81,
   getX: function() { 
     console.log( this.x) 
   }
};
var getX = obj.getX.bind(obj);//use obj as 'this';
getX();//81
var getX = function(){
  obj.getX.apply(obj); 
}
getX();//also 81

The use of bind and call/apply look very similar, I want to know what's the difference between them.The two getX Function above is the same?

解决方案

bind returns a function which will act like the original function but with this predefined. It is usually used when you want to pass a function to an event handler or other async callback.

call and apply will call a function immediately letting you specify both the value of this and any arguments the function will receive.

Your second example defines an anonymous function which calls apply. This is a common pattern; bind provides a standard implementation of that which allows you to do it with a simple function call (thus being quicker and easier to write).

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