Next 0-Z Sequence Code with Javascript

Question

I need to create a Javascript function that takes a string of letters and numbers and it returns the next count value. The count goes from 0 to Z. Example of the sequence:

0 - 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - A - B - C - D [...] Y - Z - 01 - 02 - 03 [...] 0Y - 0Z - 10 - 11 - 12 [...]

Example of the function:

nextCode ("AF10") // Returns "AF11"

nextCode ("A4ZZ") // Returns "A500"

---

What I’ve tried so far:

/*Gerar Novo Código*/
function nextCode(lastCode){
    //Verifica o Tamanho
    var codeSize = lastCode.length;
    //Verifica o index do ultimo caracter
    var indexLastValidChar = codeSize-1;
    //Se o ultimo caracter for igual a Z pega o caractere anterior (loop)
    var loopAtive;
    do {
        indexLastValidChar = loopAtive == true ?  indexLastValidChar-1 :indexLastValidChar;
        var lastValidChar = lastCode.substr(indexLastValidChar, 1);
        loopAtive = true;
    } while(lastValidChar == "Z");
    //Pega a primeira metade do novo código
    var firstHalfCode = lastCode.slice(0, indexLastValidChar);
    //Verifica se o ultimo caracter diferente de Z é numero ou letra
    var isChar = isNaN(parseInt(lastValidChar));
    //Se for char, gera o próximo caracter
    var newChar;
    if (isChar){
        newChar = String.fromCharCode(lastValidChar.charCodeAt(0)+1);
    } //Se não for, verifica se o número é 9
    else if (lastValidChar == "9") {
        newChar = "A";
    }  //Se não for, adicona um ao número
    else {
        newChar = parseInt(lastValidChar) + 1;
    }
    //Junta primeira metade
    firstHalfCode = firstHalfCode + newChar;
    //Adicona zeros ao final, caso codeSize seja diferente de indexLastValidChar+1 - ou seja, existem Zs
    for (var i = 0; i < codeSize - indexLastValidChar+1; i++) {
        var newCode = firstHalfCode + 0;
    }
    //Mostra o novo código
    console.log(newCode);
}
nextCode ("AF10");
nextCode ("A4ZZ");

The results don’t work out and I’m a little lost...

Answer 1

From the understanding of the question, it seems that you are willing to work with a 36 basis, but the sequence example described in the question does not fall right into the 36 basis. The examples of sequences of "AF10" -> "AF11" and "A4ZZ" -> "A500" are correct, but following base 36 the number after "Z" would be "10". If this is the case, just use the functions parseInt and String.prototype.toString, which allow the base to be passed per parameter.

var nextCode = function(number) {
  var inBase10 = parseInt(number, 36);
  return (inBase10 + 1).toString(36).toUpperCase();
};

nextCode('AF10'); // => "AF11"
nextCode('A4ZZ'); // => "A500"

Answer 2

If you know the String that you have of characters you can use a loop to make these changes/increments. Using flags to coltrolar if you should increment.

Suggestion:

var Next = (function(seq) {
  var lastChar = seq.slice(-1);

  return function(str) {
    if (!str) return '0';
    var chars = str.split('');
    var raize = true,
      addChar = false;
    for (var i = chars.length - 1; i + 1; i--) {
      var charIndex = seq.indexOf(chars[i]);
      if(!raize) continue;
      if (chars[i] !== lastChar) {
        if (!raize) break;
        chars[i] = seq[charIndex + 1];
        raize = false;
      } else {
        chars[i] = seq[0];
        raize = true;
        if (raize && i == 0) chars.unshift(seq[0]);
      }
    }
    return chars.join('');
  }

})('0123456789ABCDEFGHIJKLMNOPQRSTUVXYZ');

['', '00', '0Z', 'ZZ', 'AF10', 'A4ZZ', 'A4Z0'].forEach(test => console.log(test, Next(test)));