Tiny Base Conversion Method (up to base 16)

readable.js

function convertToBase (number, base) {
  var currentNumber = Math.floor(number / base),
      remainder     = number % base,
      rightChar     = '0123456789ABCDEF'.charAt(remainder),
      leftStr       = (currentNumber ? convertToBase(currentNumber, base) : '');
  return leftStr + rightChar;
}

function convertFromBase (str, base) {
  var rightChar = str.substr(-1),
      rightVal  = '0123456789ABCDEF'.indexOf(rightChar),
      leftStr   = str.slice(0, -1),
      leftVal   = leftStr ? convertFromBase(leftStr, base) : 0;
  return base * leftVal + rightVal;
}

tiny.js

function convertToBase(number,base,cn){return ((cn=~~(number/base))?convertToBase(cn,base):'')+'0123456789ABCDEF'.charAt(number%base)}

function convertFromBase(str,b,ls){return b*((ls=str.slice(0,-1))?convertFromBase(ls,b):0)+'0123456789ABCDEF'.indexOf(str.substr(-1))}