1636/index.js

Base16 to/from Base36 conversion

'use strict'

function addLeadZeros(str, pegLength) {
  if (str.length == 0) str = '0'
  while ((str.length % pegLength) > 0) {
    str = '0' + str;
  }
  return str
}

function stripLeadZeros(str) {
  while (str.length > 1 && str[0] == '0') {
    str = str.substr(1);
  }
  return str
}

function to36(base16) {
  if (typeof base16 != 'string') return
  if (base16 == '') return '0'
  base16 = addLeadZeros(base16, 5)
  var base36 = ''
  var len = base16.length
  while (len > 0) {
    var val = parseInt(base16.substr(0,5), 16)
    base16  = base16.substr(5)
    len    -= 5
    base36 += addLeadZeros(val.toString(36), 4)
  }
  return stripLeadZeros(base36)
}

function to16(base36) {
  if (typeof base36 != 'string') return
  if (base36 == '') return '0'
  base36 = addLeadZeros(base36, 4)
  var base16 = ''
  var len = base36.length
  while (len > 0) {
    var val = parseInt(base36.substr(0,4), 36)
    base36  = base36.substr(4)
    len    -= 4
    base16 += addLeadZeros(val.toString(16), 5)
  }
  return stripLeadZeros(base16)
}

module.exports = {
  to36: to36,
  to16: to16
};