function setUrlParam(oldurl,paramname,pvalue){
  var   reg   =   new   RegExp("(\\?|&)"+   paramname   +"=([^&]*)(&|$)","gi");     
  var   pst=oldurl.match(reg);     
  if((pst==undefined)||(pst==null)){    
	return   oldurl+((oldurl.indexOf("?")==-1)?"?":"&")+paramname+"="+pvalue;     
  }   
  var   t=pst[0];     
  var   retxt=t.substring(0,t.indexOf("=")+1)+pvalue;     
  if(t.charAt(t.length-1)=='&')   retxt+="&";     
  return   oldurl.replace(reg,retxt);     
}