1、一般第一时间想起的会是创建一个新的变量，作为中间值用于临时接收其中一个值，最后完成变量的转换
<script>
let a = 10;
let b = 20;
let c = a;
a = b;
b = c;
console.log(a,b);//20 10
</script>
2、通过计算也可以完成变量的转换
<script>
let a = 10;
let b = 20;
a = a + b;// a = 30
b = a - b;// b = 30 - 20 = 10
a = a - b;// a = 30 - 10 = 20
console.log(a, b);//20 10
</script>
3、es6提供了一种方法 变量的解构赋值
<script>
var a = 10;
var b = 20;
var [a, b] = [b, a]
console.log(a, b);//20 10
</script>
