rebase.js

const dictionary = '0123456789abcdefghijklmnopqrstuvwxyz'.split('')

function toBase36 (number) {
  const prefix = number < 36 ? '' : toBase36(Math.floor(number / 36))
  return prefix + dictionary[number % 36]
}

function fromBase36 (b36) {
  let val = dictionary.indexOf(b36[b36.length - 1])
  if (val === -1) return NaN

  if (b36.length > 1) {
    val += fromBase36(b36.slice(0, -1)) * 36
  }

  return val
}

module.exports = {toBase36, fromBase36}