Query string in java script

function getQuerystring(key, default_)

{

  if (default_==null) default_="";
  key = key.replace(/[\[]/,"\\\[").replace(/[\]]/,"\\\]");
  var regex = new RegExp("[\\?&]"+key+"=([^&#]*)");
  var qs = regex.exec(window.location.href);
  if(qs == null)
   return default_;
  else
    return qs[1];
}

getQuerystring(id)