es6知识点for..of vs for...in

es6知识点for..of vs for...in

默认具有遍历器接口的数据结构,for of循环 当对一个数据结构使用for of循环遍历的时候，会自动调用遍历器接口。 ES6中有四类数据结构默认具有遍历器接口: （1）数组 （2）某些类数组 （3）Map （4）Set

for of 遍历

var arr = [1,2,3,4,5,6];
	//不同循环遍历
	for(let i = 0;i<arr.length;i++){
		console.log(arr[i]);
	}
	arr.forEach(i=>{
		console.log(i);
	});

	//用迭代器遍历
	let iterator = arr[Symbol.iterator]();
	let result =iterator.next();
	while(!result.done){
		console.log(result.value);
		resulf = iterator.next();
	}
	
	//for of 遍历
	//array
	for(let item of arr){
		console.log(item);
	}
	//set
	let s = new Set(["a","b","c"]);
	for(let item of s){
		console.log(item);
	}
	//map
	let m = new Map([["name","姜姜"],["age",23]]);
	for(let item of m){
		console.log(item);
	}

---

for in

let obj = {x:1,y:2,z:3};
let arr = ["a","b","c"];
for(let key in obj){
	console.log(key);
	console.log(obj[key]);
}
for(let key in arr){
	console.log(key);
	console.log(arr[key]);
}