ES6数组的解构赋值

<script>
    //数组的解构赋值
    const arr1 = [1, 2, 3, 4]
    let [a, b, c, d] = arr1;
    //更加复杂的情况
    const arr2 = [1, 2, 3, [4, 5, [6, 7]]]//如何拿到7
    let [, , , [, , [, num]]] = arr2
    console.log(num)
    //扩展运算符...
    const arr3 = [1, 2, 3, 4]
    const arr4 = [5, 6]
    const arr5 = [...arr3, ...arr4] //合并两个数组
    const [a, b, ...c] = arr3//a=1;b=2;c=[3,4]
    //默认值
    const arr6=[1,undefined,undefined,2]
    const [a=5,b=5,c,d]=arr6 //a=1;b=5;c=undefind;d=2;只有等于undefind是有默认值
    //交换变量
    let a=5,b=6;
    [a,b]=[b,a]
    //接收多个返回值
    function getMessage(){
        return [111,222,333]
    }
    const[a,b,c]=getMessage();//a=111;b=222;c=333
</script>