function makeObject(){
   var x;
   if (window.ActiveXObject) {
      x = new ActiveXObject("Microsoft.XMLHTTP");
   }else if (window.XMLHttpRequest) {
      x = new XMLHttpRequest();
   }
   return x;
}
var request = makeObject();

var the_content;
function check_content(the_content){
   request.open('get', the_content);
   request.onreadystatechange = parseCheck_content;
   request.send('');
}
function parseCheck_content(){
   if(request.readyState == 1){
      document.getElementById('content').innerHTML = '<img src="images/cargando.gif" width="65" height="65">';
   }
   if(request.readyState == 4){
      var answer = request.responseText;
      document.getElementById('content').innerHTML = answer;
   }
}