es6 解构赋值

var a, b, rest;
[a, b] = [10, 20];
console.log(a); // 10
console.log(b); // 20

[a, b, ...rest] = [10, 20, 30, 40, 50];
console.log(a); // 10
console.log(b); // 20
console.log(rest); // [30, 40, 50]

({ a, b } = { a: 10, b: 20 });
console.log(a); // 10
console.log(b); // 20

({a, b, ...rest} = {a: 10, b: 20, c: 30, d: 40});
console.log(a); // 10
console.log(b); // 20
console.log(rest); // {c: 30, d: 40}

设置默认值

var a, b;
[a=5, b=7] = [1];
console.log(a); // 1
console.log(b); // 7

交换变量

var a = 1;
var b = 3;
[a, b] = [b, a];
console.log(a); // 3
console.log(b); // 1