SOURCE

let num = 1
let a = ++ num
let i = 3
let b = i++ + i
console.log(a <= b)
console.log(x = a++ + 5)//a++实际是2 运算结果是是2+5 只是a++本身的赋值变成了3，和计算要区分开来
console.log(x === b)
console.log(typeof i)
console.log(typeof num)