将[1,2,[3,4,[5,6],7],8]转成怎[1,2,3,4,5,6,7,8]  

1、最简单方法

[1,2,[3,4,[5,6],7],8].toString().split(',')

// ->["1", "2", "3", "4", "5", "6", "7", "8"]

2、reduce递归

function toArray(a){
    return a.reduce((res,current)=>{
        return Array.isArray(current)?[...res,...toArray(current)]:[...res,current]
    },[])
}
toArray([1,2,[3,4,[5,6],7],8])

// -->[1, 2, 3, 4, 5, 6, 7, 8]

3 、字符串

JSON.stringify([1,2,[3,4,[5,6],7],8]).replace(/\[|\]/g,'').split(',')

// -->[1, 2, 3, 4, 5, 6, 7, 8]