generateAlphaNumeric.js

function generateAlphaNumericLabels(amount) {
  var labels = [];

  for (var i = 0; i <= amount; i++) {
    var appendNumber = 0;
    var offset = 0;

    if (i > 25 && i <= 34) {
      appendNumber = i - 25;
      labels.push(String.fromCharCode(65 + offset) + appendNumber);
    } else if (i > 33) {
      offset = Math.floor((i - 26) / 10);
      appendNumber = i - (25 + (offset * 10));
      labels.push(String.fromCharCode(65 + offset) + appendNumber);
    } else {
      labels.push(String.fromCharCode(65 + i));
    }
  }
  return labels;
}

If you wish to change it to the headers on excel documents for example, like continuous headers ["A",..."Z","A1",..."Z1","A2" ...] is really simple the change

function generateAlphaNumericLabels(amount) {
  var labels = [];
  for (var i = 0; i <= amount; i++) {     
      if (i > 25) {
        labels.push(String.fromCharCode(65 + (i % 26)) + Math.floor(i/26));
      } else {
        labels.push(String.fromCharCode(65 + i));
      }
  }
  return labels;
}