1.新增includes
let arr = [1,2,3,4,5]
arr.includes('3') => true
2.求幂运算**
5**12 === Math.pow(5,12) =>true
3.字符填充函数padStart 和 padEnd
padStart()
在开始部位填充,返回一个给出长度的字符串,填充物给定字符串,把字符串填充到期望的长度
console.log('0.00'.padStart(20))
console.log('10,000.00'.padStart(20))
console.log('250,000.00'.padStart(20))
console.log('0.00'.padEnd(20))
console.log('10,000.00'.padEnd(20))
console.log('250,000.00'.padEnd(20))
4.异步处理语法糖Generator