mongoid_to_rad66.js

'use strict'

var int = require('int')

function hexToDec (s) {
  const map = '0123456789abcdef'
  let power = 0
  let res = 0
  for (let i = s.length - 1; i >= 0; i--) {
    const currentDigit = s.substr(i, 1)
    res = int(res).add(
      int(map.indexOf(currentDigit)).mul(int(16).pow(power))
    )
    power++
  }
  return(res.toString())
}

function decToRadix(num, radix) {
  const map = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-_.~'
  radix = radix || (map.length - 1)
  let hex = ''
  let chrPos
  num = int(num)
  while (!num.eq(0)) {
    chrPos = int(num).mod(radix).toString() * 1
    hex = map.charAt(chrPos) + hex
    num = int(num.sub(chrPos).toString()).div(radix)
  }
  return hex
}

console.log(hexToDec('12345678ff24') === '20015998369572')
console.log(hexToDec('f5345ff324ffffffffff') === '1157945932905430848110591')
console.log(hexToDec('507f191e810c19729de860ea') === '24912452986661892666266509546')

const id = '507f191e810c19729de860ea'
console.log(id)
console.log(decToRadix(hexToDec(id))) // "p9P2GoMRqPBhfMQq"