// JavaScript Document
//globals 
var first = "make"; //id of first SELECT 
var second = "model"; //id of second SELECT 
// 
function sendRequest(url,params,HttpMethod) { 
if(!HttpMethod) { //check if http method is defined, if not, set it to GET 
HttpMethod="GET"; 
} 
// 
// initialize request object 
req=null; 
if(window.XMLHttpRequest){ 
req=new XMLHttpRequest; //mozilla/safari 
} else if(window.ActiveXObject){ 
req=new ActiveXObject("Microsoft.XMLHTTP"); //internet explorer 
} 
// 
//define callback handler 
if(req) { 
// 
req.onreadystatechange=onReadyState; 
req.open(HttpMethod,url,true); 
req.setRequestHeader("Content-Type","application/x-www-form-urlencoded"); 
req.send(params); 
} 
} 
// 
function onReadyState() { 
// 
var ready=req.readyState; 
var data=null; 
if(ready==4){ //check ready state 
data=req.responseText; //read response data 
var items = data.split(','); 
var length = items.length; 
for(var i = 0; i < length; i++) { 
var childEl = document.createElement('option'); //create option 
var El = document.getElementById(second); 
El.appendChild(childEl); //then append it to the second dropdown list 
childEl.value = items[i]; 
childEl.innerHTML = items[i]; 
} 
} 
} 
// 
function clicked() { 
// 
var ty = document.getElementById(first0);
var selected0 = ty.selectedIndex;
var el = document.getElementById(first); 
var ob2=document.getElementById(second); 
var selected = el.selectedIndex; 
// 
while(ob2.hasChildNodes()) { //removes items from dropdown if some already exist 
ob2.removeChild(ob2.firstChild); 
} 
//if(selected!= 0) { //if they choose something other than the first select-->"Select topic first" 
sendRequest('fetch.php?yr='+ty.options[selected0].value+'&topic='+el.options[selected].value); 
ob2.disabled=0; 
/*} else { //otherwise add the Select Topic First option and disable it 
var childEl = document.createElement('option'); 
ob2.appendChild(childEl); 
childEl.innerHTML = 'Select Make First'; 
ob2.disabled=1; 
}*/ 
}