javascript对象、this、作用域和闭包的问题。（相同变量名查找问题）？

以下几段代码，输出的结果不一样。希望有大神可以解答一下原理，谢谢！

var myvar = "TheWindow"; var object = { myvar : "MyObject", getVar : function(){ return function(){ return myvar; }; } }; console.log(object.getVar()());//输出TheWindowfunction MyCont(){ var myvar = "MyObject"; this.getVar = function(){ return function(){ return myvar; }; } } var obj = new MyCont(); console.log(obj.getVar()());//输出MyObject

然后我修改了一下，加上了this，输出结果又不同了。

var myvar = "TheWindow"; var object = { myvar : "MyObject", getVar : function(){ return function(){ return this.myvar;//此处加入了this，依旧输出TheWindow }; } }; console.log(object.getVar()()); function MyCont(){ var myvar = "MyObject"; this.getVar = function(){ return function(){ return this.myvar;//此处加入了this，输出变成了TheWindow，而不是原先的MyObject }; } } var obj = new MyCont(); console.log(obj.getVar()());

然后我再改一下

var myvar = "TheWindow"; var object = { myvar1 : "MyObject", getVar : function(){ return function(){ return myvar1;//虽然object内含有myvar1属性，但是这样写会报优艾设计网_PS交流错,但是如果写this.myvar1的话就不报错，输出undefined }; } }; console.log(object.getVar()()); var myvar = "TheWindow"; var object = { myvar : "MyObject", getVar : function(){ return myvar;//此处去掉了function，还是输出TheWindow } }; console.log(object.getVar()); var myvar = "TheWindow"; var object = { myvar : "MyObject", getVar : function(){ return this.myvar;//对比上面，加入了this，则输出的是对象属性MyObject } }; console.log(object.getVar());

最后还是要感谢一下，好心人帮忙解答问题，万分感谢！