闭包中的this

Question

varname="thewindow";varobject={name:"myobject";getName:function(){returnthis.name;}};object.getName();//"myobject"(object.getName)();//"myobject"(object.getName=object.getName)();//"thewindow"第二和第三个输出为什么不一样，尤其是第三个，怎么理解？