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);
    }
}