Javascript get Querystring value

function getQuerystringval(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];
}

link: http://www.google.com/?id=12

var id = getQuerystring(‘id’);