js中Object.defineProperties 定义一个在原对象可读可写的方法

function A(){
   this.name = 'hellow word';
}

Object.defineProperties(
  A.prototype,{
  doSomething2 : {
    value: function(parm){
      console.log(parm)
    },
    enumerable: true,
    configurable: true,
    writable: true
  }
})

var a2 = new A()

a2.doSomething2(232);

Object.defineProperties(obj,{
  "sex":{
     value:"ajia",
     writable:true,
     enumerable:true,
     configurable:true
   },
   "age":{
      value:26,
      writable:true,
      enumerable:true,
      configurable:true
   },
    "name":{
      value:"ajia",
      writable:true,
      enumerable:true,
      configurable:true
   }
})

//Object.defineProperty()的用法
var _value = null;
var obj = {};
[].forEach.call(str,function(v,i,arr){
   Object.defineProperty(obj,v,{
     get:function(){return _value;},
     set:function(newVal){return _value = newVal;},
     enumerable:true,
     configurable:true
   })
})