Plus one [https://leetcode.com/problems/plus-one]

plus_one.js

/**
 * @param {number[]} digits
 * @return {number[]}
 */
var plusOne = function(digits) {
    let index = digits.length - 1;

    while (index >= 0) {
        if (digits[index] + 1 <= 9) {
            digits[index] =  digits[index] + 1;

            break;
        }

        digits[index] = 0;
        index--;
    }

    if (digits[0] === 0) {
        digits[0] = 1;
        digits.push(0);
    }
 
    return digits;
};