js 对call apply bind理解

Posted 2020-10-05 上帝不是要你成功，而是让你去尝试

请参考 http://www.cnblogs.com/xljzlw/p/3775162.html


1.call和apply的区别：参数类型不同
var mtt = {
    name: "mtt",
    sayHello: function (age) {
         console.log("hello, i am ", this.name + " " + age " years old");
     }
};

var  xjs = {
    name: "xjs ",
};

mtt.sayHello(24);// hello, i am zlw 24 years old

apply参数需要是数组形式，而call参数需要用逗号隔开24,25

mtt .sayHello.call(xjs , 24);// hello, i am xjs 24 years old
mtt .sayHello.apply(xjs , [24]);// hello, i am xjs 24 years old

bind方法传递给调用函数的参数可以逐个列出，也可以写在数组中。bind方法与call、apply最大的不同就是前者返回一个绑定上下文的函数

mtt .sayHello.bind(xjs)(24); //hello, i am xlj 24 years old
mtt .sayHello.bind(xjs)([24]); //hello, i am xlj 24 years old

2.bind

var bind = Function.prototype.call.bind(Function.prototype.bind);

var zlw = {
 name: "zlw" 
};

function hello () {
  console.log("hello, I am ", this.name);
}

bind(hello, zlw)() // hello, I am zlw