if(document.getElementsByClassName == undefined) 
{ 
   document.getElementsByClassName = function(cl) 
   { 
      var retnode = []; 
      var myclass = new RegExp('\\b'+cl+'\\b'); 
      var elem = this.getElementsByTagName('*'); 
      for (var i = 0; i < elem.length; i++) { 
         var classes = elem[i].className; 
         if (myclass.test(classes)) { 
            retnode.push(elem[i]); 
         } 
      } 
      return retnode; 
   } 
}; 

function refcapt()
{
	var newcapt = document.getElementById("captcha").src;
	document.getElementById('captcha').src= newcapt+'&'+Math.random();
}