function ajax(url, vars,callback){ 
var request = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("MSXML2.XMLHTTP.3.0");
 
        request.open("POST", url, true);
        request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");
        request.setRequestHeader("Content-length", vars.length);
 
        request.onreadystatechange = function(){ 
                if (request.readyState == 4 && request.status == 200) { 
                    if (request.responseText){
                        callback(request.responseText);
                    }
                }
        };
        request.send(vars);
}


//This function tests if the input by the user isn't to long.
//Returns error message if so.
function validate_textField(word){
	var maxlenghtText = 64;
	if(word.length == 0){
		alert("Please enter a word.");
		return false;
	}
	else if(word.length >= maxlenghtText){
		alert("Sorry, your word was too long.");
		return false;
	}
	else
	return true;
}

function ajaxLogin(url, vars,callback){ 
var request = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject("MSXML2.XMLHTTP.3.0");
        request.open("POST", url, true);
        request.setRequestHeader("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");
        request.setRequestHeader("Content-length", vars.length);
 
        request.onreadystatechange = function(){ 
                if (request.readyState == 4 && request.status == 200) { 
                    if (request.responseText){
						callback(request.responseText);
					}
                }
        };
        request.send(vars);
}