numbers-words/src/functions/toOrdinal.js

numbers-words is a useful package when you are working with numbers. It can converts numbers to words, format numbers and more in the upcoming versions!

const maxNumber = require("../core/maxNumber.js");
function toOrdinal(number) {
  if (isNaN(number)) throw new Error("Expected a number");
  if (number > maxNumber) throw new Error("Number can not be greater than" + maxNumber);

  let idkWhatToName = number.toString();
  let lastDigit = idkWhatToName.slice(-1);
  let lastTooDigits = idkWhatToName.slice(-2);
  // Very kawai name
  if (["11", "12", "13"].includes(lastTooDigits)) {
    return `${number}th`;
  }

  if (lastDigit === "1") return `${number}st`;
  if (lastDigit === "2") return `${number}nd`;
  if (lastDigit === "3") return `${number}rd`;
  return `${number}th`;
}

module.exports = toOrdinal