var request = null;
 var id_p;
 
   function createRequest() {
     try {
       request = new XMLHttpRequest();
     } catch (trymicrosoft) {
       try {
         request = new ActiveXObject("Msxml2.XMLHTTP");
       } catch (othermicrosoft) {
         try {
           request = new ActiveXObject("Microsoft.XMLHTTP");
         } catch (failed) {
           request = null;
         }
       }
     }

     if (request == null)
       alert("Error creating request object!");
   }

function str_replace(substr,newsubstr,str) {
 replace_count=0;
 while (str.indexOf(substr)>=0) {
   str=str.replace(substr,newsubstr);
   replace_count++;
 }
 return(str);
}