Plus One.js

/*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.*/

/**
 * @param {number[]} digits
 * @return {number[]}
 */
var plusOne = function(digits) {
    // var num = Number.parseInt(digits.join(''))
    // return (""+(num+1)).split('').map(Number)
    for(var i=digits.length-1; i>=0; i--){
        if(digits[i] != 9){
            digits[i]++
            return digits
        }
        else{
            digits[i] = 0
        }
    }
    digits.unshift(1)
    return digits
};