1、call

Function.prototype.myCall = function (context) {    var c = context || window    var args = Array.from(arguments).slice(1)        c.___fn = this    var result = c.___fn(...args)    delete c.___fn    return result  }复制代码

2、apply

Function.prototype.myApply = function (context) {    var c = context || window    c.__fn = this        var args = Array.from(arguments)[1]    var result = args ? c.__fn(...args) : c.__fn()    delete c.__fn    return result  }复制代码

3、bind

Function.prototype.myBind = function (context) {    var _this = this    var oldArgs = Array.from(arguments).slice(1)    return function () {      var finArgs = oldArgs.length ? oldArgs : Array.from(arguments)      return _this.apply(context, finArgs)    }  }复制代码