添加__ob__属性，值为观察者函数def(obj,key,val,enumerable){//obj为观察数据对象，eg:{a:1}//key为__ob__//val为观察者{dep:Dep{id:2subs:[]},value:{a:1},vmCount:0,}Object.defineProperty(obj,key,{value:val,enumerable:!!enumerable,writable:true,可配置：真});}/***遍历所有属性并将它们转换为*getter/setter。仅当*值类型为Object时才应调用此方法。*/Observer.prototype.walk=functionwalk(obj){varkeys=Object.keys(obj);对于(vari=0;i
