var n = 'window' 
var o = { 
     n: 'my', 
     myfunc: function() { 
         console.log(this.n); 
     }, 
     myfun2: function() {

         //箭头函数可以
         return () => { 
             console.log(this.n); 
         } 
     }, 
     myfun3: function() {

         //闭包
         var that = this; 
         return function() {
             console.log(that.n); 
         } 
     } 
     myfun4: function() {

         //bind
         return (function() {
             console.log(this.n)
         }).bind(this)
     } 
};