ES6学习笔记15 Iterator和for...of 循环

{
let arr=['hello','world']
let map=arr[Symbol.iterator]()

console.log(map.next())
console.log(map.next())
console.log(map.next())
}

{
let obj={
start:[1,2,5],
end:[6,7,8],
[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
}
}else{
return{
value:arr[index++],
done:true
}
}
}
}
}
}

for(let key of obj){
console.log(key)
}

}

{
let arr=['hello','world']
for(let val of arr){
console.log(val)
}
}