ES7

1. 指数运算符(幂): **
2. Array.prototype.includes(value) : 判断数组中是否包含指定value

        console.log(2 ** 3);//8

    let arr = [1,4,5,6,'abc'];
    console.log(arr.includes('a'));//false
    console.log(arr.includes('abc'));//true
    console.log(arr.includes(4));//true