for ..in 跟 for ..of的区别

1.for ... in是遍历数组、对象的key

let arr = [1, 2, 3];

for (let i in arr) {

console.log(i)  // 0 1 2

 }

let obj = {

name: 'zhangsan',

age: 18,

};

for (let i in obj) {

console.log(i) //name  value

}

2.for ... of是遍历数组value

let obj = [1,2,3]

for (let i of obj) {

console.log(i) //zhangsan  18

}