combine UIDs

combineUIDs.js

function combineUIDs(o)
{
  function cu(a, b)
  {
    function cc(a, b)
    {
      if (a === '-') return '-';
      return Number(parseInt(a, 16) ^ parseInt(b, 16)).toString(16);
    }
    var i = 0,
      n = a.length,
      c = '';
    for ( ; i < n; ++i)
    {
      c += combineChars(a.charAt(i), b.charAt(i));
    }
    return c;
  }
  var c = null;
  for (var uid in o)
  {
    c = (c === null) ? uid : cu(c, uid);
  }
  return c;
}