js 在函数中遇到的this指向问题

//自执行函数的调用三种/*!function(){alert(123)}();(function(){alert(345)}())(function(){Array.prototype.push.call(arguments,3);console.log(arguments)//输出 [1,2,3]})(1,2)*/var obj = {a:1,b:function(){console.log(this);}}obj.fn = function(){console.log(this);//===obj}obj.fn();obj.b();//this==obj//var c = obj.b();//this==obj//c();//this==window;Function.prototype.bind = function(context){var self = this;console.log(‘测试bind‘)console.log(this); // function(){var c = 1}return function(){return ?self.apply(context,arguments)}}var o = {name:‘my name id huhu‘}var func = function(){alert(this.name)}.bind(o);console.log(func) ?//function(){return self.apply(context,argument)}func(); ?