<!-- -------------------------------- SELEÇÃO PARA BROWSERS --------------------------------------//>
var xmlhttp = bunda();
function bunda(){
if(window.XMLHttpRequest){
return new XMLHttpRequest();
}else if(window.ActiveXObject)
{
return new ActiveXObject("Microsoft.XMLHTTP");
}
}
<!-- ------------------------------------ ALTERA URL ---------------------------------------------//>
function alteraURL(url, olugar){
	document.getElementById("carregando").style.display="";
    xmlhttp.open("GET", url, true);
    xmlhttp.onreadystatechange = function(){
      if(xmlhttp.readyState==4){
				if (xmlhttp.status == 200) {
					// Pega o conteúdo - HTML - da página requisitada: formulario.php?ajax=true e coloca dentra da div definida na variável recipiente
					document.getElementById(olugar).innerHTML = xmlhttp.responseText;
					document.getElementById("carregando").style.display="none";	
				} // if-status->200
			} // if->readyState->4
 }
   xmlhttp.send(null);
}
<!-- --------------------------------- ALTERA DESTAQUE -------------------------------------------//>
function alteraDestaque(url){
    xmlhttp.open("GET", url, true);
    xmlhttp.onreadystatechange = function(){
      if(xmlhttp.readyState==4){
	  document.getElementById("destaque").innerHTML = xmlhttp.responseText;
  }
 }
   xmlhttp.send(null);
}
<!-- --------------------------------- ALTERA VARIADOS ---------------------------------------------//>
function alteraVariados(url){
    xmlhttp.open("GET", url, true);
    xmlhttp.onreadystatechange = function(){
      if(xmlhttp.readyState==4){
	  document.getElementById("variados").innerHTML = xmlhttp.responseText;
  }
 }
   xmlhttp.send(null);
}
<!-- --------------------------- FAZ TROCAR DESTAQUE e VARIADOS------------------------------------//>
function AlteraAuto(){
window.setTimeout("alteraDestaque('site_destaque.php?ajax=ajax')", 8000);
window.setTimeout("alteraVariados('site_ofertas_variadas.php?ajax=ajax')", 12000); 
setTimeout("AlteraAuto()", 10000)}

<!-- --------------------------------- ----------------- -------------------------------------------//>
function limpar(objeto, msg) {
    if (objeto.value == msg)objeto.value = '';
}

function mostrar(objeto, msg) {
    if (objeto.value == '')objeto.value = msg;
}
<!-- --------------------------- Quantidade máxima de caracteres ----------------------------------//>
function textCounter(field, countfield, maxlimit) {
if (field.value.length > maxlimit)
field.value = field.value.substring(0, maxlimit);
else 
countfield.value = maxlimit - field.value.length;
}

<!-- --------------------------- Submeter Form com Javascript ----------------------------------//>

function submitform(NomeForm)
{
    document.forms[NomeForm].submit();
}


function AtivaDiv(ativa, desativa){
document.getElementById(ativa).style.display    ='block';
document.getElementById(desativa).style.display ='none';
}