求幂运算符
let a = 7 ** 12
let b = 2 ** 7
console.log(a === Math.pow(7,12)) // true
console.log(b === Math.pow(2,7)) // true
//
let a = 7
a **= 12
let b = 2
b **= 7
console.log(a === Math.pow(7,12)) // true
console.log(b === Math.pow(2,7)) // true
另一种写法
let a = 7
a **= 12
let b = 2
b **= 7
console.log(a === Math.pow(7,12)) // true
console.log(b === Math.pow(2,7)) // true
includes方法
//包含数组里的数,打印true。
//不包含数组里的数,则打印false。
var aa=[1,2,3];
console.log(aa.includes(5));//false
console.log(aa.includes(3));//true
字符填充函数padStart 和 padEnd
padStart()
console.log('react'.padStart(10).length) // " react" is 10
console.log('backbone'.padStart(10).length) // " backbone" is 10
padEnd
console.log('react'.padEnd(10, ':-)')) // "react:-):-" is 10
console.log('backbone'.padEnd(10, '*')) // "backbone**" is 10