方法一.ES6解构

let [a,b] = [10,20];
[a,b] = [b,a]

方法二.利用数组特性进行交换

let a = 10 , b = 20;
a = [a,b]
b = a[0]
a = a[1]

方法三.算数运算(这个确保是number类型)

let a = 10 , b = 20;
a = a + b
b = a - b
a = a - b