function parseQueryString (str) {
  str = str ? str : location.search;
  var query = str.charAt(0) == '?' ? str.substring(1) : str;
  var args = new Object();
  if (query) {
    var fields = query.split('&');
    for (var f = 0; f < fields.length; f++) {
      var field = fields[f].split('=');
      args[unescape(field[0].replace(/\+/g, ' '))] = unescape(field[1].replace(/\+/g, ' '));
    }
  }
  return args;
}