function getAjax()
{
	var xmlhttp = false;
	
	try
	{
		xmlhttp = new ActiveXObject("Msxml2.XMLHTTP");
	}
	catch (e)
	{
		try
		{
        	xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
       	}
       	catch (E)
       	{
       		xmlhttp = false;
	  	}
	}
	
	if (!xmlhttp && typeof XMLHttpRequest!='undefined')
	{
		xmlhttp = new XMLHttpRequest();
	}
	
	return xmlhttp;
}

function comprobarDisponibilitat()
{
	var nom = document.getElementById('nom').value;
	var ajax = getAjax();
	ajax.open('GET', '/comprobarDisponibilitat?nom=' + nom, true);
	ajax.onreadystatechange = function()
	{
		if (ajax.readyState == 4)
		{
			if (ajax.status==200)
			{
				var xml = ajax.responseXML.documentElement;
				var tag = document.getElementById('disponibilitat');
				tag.setAttribute('class', xml.getElementsByTagName('estil')[0].firstChild.data);
				tag.innerHTML = xml.getElementsByTagName('missatge')[0].firstChild.data;
			}
		}
	}
	
	ajax.send(null);
}