多维数组最深层级

function deepLevel(arr){
    let res = new Array(arr.length).fill(0)
    for(let i = 0,len = arr.length;i < len;i++){
        let item = arr[i]
        res[i]++
        if(Array.isArray(item)){
            res[i] += deepLevel(item)
        }
    }
    return Math.max(...res)
}