// get query params and register click
var getps = qs();
if (getps['vi']) regclick(getps['vi']);    

// gets query parameters
function qs() {
  var qsParm = new Array();
  var query = window.location.search.substring(1);
  var parms = query.split('&');
  for (var i=0; i<parms.length; i++) {
    var pos = parms[i].indexOf('=');
    if (pos > 0) {
      var key = parms[i].substring(0,pos);
      var val = parms[i].substring(pos+1);
      qsParm[key] = val;
    }
  }
  return qsParm;
} 

// register a clickthrough (via Ajax call)
function regclick(vi){
  var xmlHttp;
  try {  // Firefox, Opera 8.0+, Safari  
    xmlHttp=new XMLHttpRequest();
  }
  catch (e) {  // Internet Explorer  
    try {    
    xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");    
    }
    catch (e) {
      try {
        xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");      
	  }
      catch (e) {
	    return false;      
	  }
    }
  }
  xmlHttp.onreadystatechange=function() {
    if(xmlHttp.readyState==4) {
	  clickResponse(xmlHttp.responseText);
    }
  }
  var rn = "gcac" + (Math.random()*1234567);
  xmlHttp.open("GET",("/clicked.php?vi="+vi+"&rn="+rn),true);
  xmlHttp.send(null);  
}

// response from click reg
function clickResponse(responseText){
}