prototype 原型链

 1 //        方法1
 2             var aa=function(){
 3                 function bb(){
 4                     this.name="1111";
 5                     console.log(this.name)
 6                 };
 7                 bb.prototype={
 8                     init:function(){
 9                         console.log('bbb')
10                     }
11                 };
12                 return new bb;
13             }
14             new aa().init();
15 
16 
17 //        方法2
18             var aa=function(){
19             }
20             aa.prototype={
21                 add:function(x,y){
22                     return x+y;
23                 },
24                 subtract:function(x,y){
25                     return x-y;
26                 }
27             }
28             console.log(new aa().add(1,3))
29 
30 
31 //        方法3
32             var aa=function(){
33                 
34             }
35             aa.prototype = function () {
36                 add = function (x, y) {
37                     return x + y;
38                 },    
39                 subtract = function (x, y) {
40                     return x - y;
41                 }
42                 return {
43                     add: add,
44                     subtract: subtract
45                 }
46             }();
47             console.log(new aa().add(1,3))