for_of循环

for(let value of target){}循环遍历

1. 遍历数组
2. 遍历Set
3. 遍历Map
4. 遍历字符串
5. 遍历伪数组

    let arr = [1,2,3,4,5,5,6,2];
    let arr1 = [];
    let set = new Set(arr);
    for(let i of set){
        console.log(i);
        arr1.push(i);
    }
    console.log(arr1);
    let map = new Map([['aaa', 'username', 25], [36, 'age']]);
    for(let i of map){
        console.log(i);
    }