//AJAX FUNCTIONS!


function GetXmlHttpObject(){ 
	var objXMLHttp=null;
	if (window.XMLHttpRequest){
		objXMLHttp=new XMLHttpRequest();
	}else if (window.ActiveXObject){
		objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP");
	}	
	return objXMLHttp;
} 



var xmlHttp_loadLetters;
//checks the answer of the given question against the selected answer
function loadLetters(letter, letterNum, expression, color){
	
	if(letter == null || letter == ""){
		return;	
	}	
	
	xmlHttp_loadLetters=GetXmlHttpObject();
	if (xmlHttp_loadLetters==null){
		alert ("Browser does not support HTTP Request")
		return
	} 
	
		
	var url="includes/xmlHttp.php?action=load_letters&letter="+letter+"&letter_num="+letterNum+"&expression="+expression+"&color="+color;
	url=url+"&sid="+Math.random();
	
	document.getElementById('letterGallery').innerHTML = 'Loading<br /><br /><img src="images/loading.gif">';
	
	//xmlHttp_loadLetters.onreadystatechange=stateChanged_loadLetters;
	xmlHttp_loadLetters.onreadystatechange=function(){
		if (xmlHttp_loadLetters.readyState==4 || xmlHttp_loadLetters.readyState=="complete"){ 
			document.getElementById('letterGallery').innerHTML = xmlHttp_loadLetters.responseText;
		}
	}
	xmlHttp_loadLetters.open("GET",url,true);
	xmlHttp_loadLetters.send(null);	
	
}