JS20 数组扁平化

JS20 数组扁平化

题解：递归数组判断

let newarr = []
const _flatten = arr => {
    // 补全代码
    let i = 0;
    while(i < arr.length) {
        if (Array.isArray(arr[i])) {
            _flatten(arr[i])
        } else {
            newarr.push(arr[i])
        }
        i++
    }
    return newarr
}