实现javaScript对象属性私有

 1  　　function Calculator(){
 2         this.num = 102;
 3     }
 4     Calculator.prototype = function () {
 5         add = function (x, y) {
 6             console.log(subtract(2,1))
 7             return x + y + this.num;
 8         },
 9 
10         subtract = function (x, y) {
11             return x - y;
12         }
13         return {
14             add: add,
15             sub: subtract
16         }
17     } ();
18 
19     var calculator = new Calculator();
20     console.log(calculator.add(1,2))
21     console.log(calculator.sub(1,2))