ES6学习笔记六（Iterator和for..of）

{let arr=['hello','world'];let map=arr[Symbol.iterator]();  //返回false时继续执行，true停止执行！
    console.log(map.next());console.log(map.next());console.log(map.next());
}{let obj={start:[1,3,2],end:[7,8,9],[Symbol.iterator](){let self=this;let index=0;let arr=self.start.concat(self.end);let len=arr.length;return {next(){if(index<len){return {value:arr[index++],done:false  //fasle会继续执行
                        }}else {return {value:arr[index++],done:true //truee会结束
                        }}}}}}for(let key of obj){console.log(key);}
}