XMLHttpRequest ne marche que pour FireFox et Safari ??

var ouvrir = "base_de_donnees_1.txt"; 
var test=null;
try
   {
     test = new XMLHttpRequest(); 
   } catch(e)
   { 
     try { test = new ActiveXObject("Msxml2.XMLHTTP"); } 
     catch (e2)
    { 
       try { test = new ActiveXObject("Microsoft.XMLHTTP"); } 
       catch (e) {}
    }
  }
test.open("GET",ouvrir,true); 
test.send(null);
var txt=test.responseText.split(":");// séparateur 

var ouvrir = "base_de_donnees_1.txt"; 
var test = new XMLHttpRequest();
test.open("GET",ouvrir,true); 
test.send(null);
var txt=test.responseText.split(":");// séparateur 

<script type="text/javascript">
ouvrir = "base_de_donnees_1.txt"; 
function funcouvrir(position)
{
var xhr_object = null;
if(window.XMLHttpRequest) xhr_object = new XMLHttpRequest();
else
if (window.ActiveXObject) xhr_object = new ActiveXObject("Microsoft.XMLHTTP");
xhr_object.open("GET", ouvrir, true);
xhr_object.onreadystatechange = function(){
if ( xhr_object.readyState == 4 )
{
document.getElementById(position).innerHTML = xhr_object.responseText.split(":");
}
}
xhr_object.send(null);
}
</script>
<script language="JavaScript">
     //déclaration des variables
var public
var runningpub
var speed = 5000;
    //requête publique une fois
function main(){
public = window.setTimeout('funcouvrir("madiv")', 0001);
}
    //boucle publique
function startboucle(){
runningpub = setInterval( function(){window.setTimeout('funcouvrir("madiv")', 1000);},speed);
}
  
   //lancement des fonctions
main()
startboucle()
</script>

<div id="madiv"></div>