MediaWiki:NumerAlpha.js

// from: https://stackoverflow.com/questions/9083037/convert-a-number-into-a-roman-numeral-in-javascript
// To be used in Template:CardCatalog and other places as well

function mainFunc() {
  function romanize(num) {
    if (isNaN(num)) return NaN;
    const digits = String(+num).split(""),
      key = [
        "",
        "C",
        "CC",
        "CCC",
        "CD",
        "D",
        "DC",
        "DCC",
        "DCCC",
        "CM",
        "",
        "X",
        "XX",
        "XXX",
        "XL",
        "L",
        "LX",
        "LXX",
        "LXXX",
        "XC",
        "",
        "I",
        "II",
        "III",
        "IV",
        "V",
        "VI",
        "VII",
        "VIII",
        "IX",
      ];
    let roman = "";
    let i = 3;
    while (i--) roman = (key[+digits.pop() + i * 10] || "") + roman;
    return Array(+digits.join("") + 1).join("M") + roman;
  }

  const incrementElemsNumeral = document.querySelectorAll(
    ".increment-numeralpha-numeral"
  );

  for (let [i, element] of incrementElemsNumeral.entries()) {
    element.innerHTML = `${++i}. ${element.innerHTML}`;
  }

  const incrementElemsRoman = document.querySelectorAll(
    ".increment-numeralpha-roman"
  );

  for (let [i, element] of incrementElemsRoman.entries()) {
    element.innerHTML = `${romanize(++i)}. ${element.innerHTML}`;
  }
}

if (document.readyState === "complete" || document.readyState !== "loading") {
  mainFunc();
} else {
  document.addEventListener("DOMContentLoaded", mainFunc);
}