Plus One

Given a non-negative integer represented as a non-empty array of digits, plus one to the integer.

You may assume the integer do not contain any leading zero, except the number 0 itself.

The digits are stored such that the most significant digit is at the head of the list.

var plusOne = function(digits) {    var len = digits.length;    for(var i = len - 1; i  >= 0; i-- ){        if(digits[i] < 9) {            digits[i] ++            return digits;        }else{            digits[i] = 0        }    }    var newArr = digits;    newArr.unshift(1);    return newArr};