var codAjax;

function criaObjAjax()
{
	try
	{ 
		ajax = new XMLHttpRequest();
	}
	catch(e)
	{ 
		try
		{ 
			ajax = new ActiveXObject("Msxml2.XMLHTTP");
		} 
		catch(e)
		{ 
			try
			{
				ajax = new ActiveXObject("Microsoft.XMLHTTP");
			}
			catch(e)
			{
				alert("Seu navegador não tem suporte AJAX, recomendo atualizar para o firefox");
				return false;
			} 
		} 
	}
	
	return ajax;
}



function chamaAjax(url,div,imgLoad)
{ 
	if (url == null) return false;
	/*if (imgLoad != null) imgLoad = '<img src="'+imgLoad+'">';*/
	var ajax = criaObjAjax();
	
	ajax.onreadystatechange = function ()
	{
		document.getElementById(div).src = imgLoad;
		/*
		if(ajax.readyState == 0 && div != null) document.getElementById(div).innerHTML = imgLoad+' Criando...';
		if(ajax.readyState == 1 && div != null) document.getElementById(div).innerHTML = imgLoad+' Solicitando...';
		if(ajax.readyState == 2 && div != null) document.getElementById(div).innerHTML = imgLoad+' Aguardando...';
		if(ajax.readyState == 3 && div != null) document.getElementById(div).innerHTML = imgLoad+' Carregando...';
		*/
		if(ajax.readyState == 4)
		{ 
			codAjax = ajax.responseText;
			/*if (div != null)document.getElementById(div).innerHTML = 'Concluido!';*/
			eval("document.getElementById('" + div + "').src = codAjax");			
			codAjax = '';
		} 
	}
	//ajax.setRequestHeader("Content-Type", "multipart/x-mixed-replace");
	ajax.open("GET",url,true); 
	ajax.send(null); 
} 

// exemplo de como chamar o ajax assíncrono
// chamaAjax('url','id','imagem');