function createXhrObject() {
	if (window.XMLHttpRequest) {
	    return new XMLHttpRequest();
	}
	else if (window.ActiveXObject) {
	    var names = [
	        "Msxml2.XMLHTTP.6.0",
	        "Msxml2.XMLHTTP.3.0",
	        "Msxml2.XMLHTTP",
	        "Microsoft.XMLHTTP"
	    ];
	    for(var i in names) {
	        try{ return new ActiveXObject(names[i]); }
	        catch(e){}
	    }
	}
	//window.alert("Votre navigateur ne prend pas en charge l'objet XMLHTTPRequest.");
	return null; // non supporté
}

function affpub() {
	var xhr = createXhrObject();
	xhr.open("POST", "choixpubs.php", true);
	xhr.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");

	xhr.onreadystatechange = function() {
		if(xhr.readyState == 4) {
		    document.getElementById("pubs").innerHTML = xhr.responseText;
		}
	}
	xhr.send("");
	setTimeout("affpub()",15000);
}