var cache = "";

function getXhr(){
	if(window.XMLHttpRequest) // Firefox et autres
		return new XMLHttpRequest(); 
	else if(window.ActiveXObject){ // Internet Explorer 
		try {
			return new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			return new ActiveXObject("Microsoft.XMLHTTP");
		}
	}
	else { // XMLHttpRequest non supporté par le navigateur 
		alert("Votre navigateur ne supporte pas les objets XMLHTTPRequest..."); 
	} 
}

function navig(rub){
	var page = "";
	switch(rub){
		case 'accueil': page = "navig.php";
		break;
		default: page = "navig.php";
	}
	
	//if(cache != rub){
		xhr= getXhr();
		xhr.onreadystatechange = function(){
			if(xhr.readyState == 4 && xhr.status == 200){
				reponse = xhr.responseText;
				document.getElementById('barre').style.display='block';
				document.getElementById('barre').innerHTML=reponse;
				cache = rub;
			}
		}

		xhr.open("POST",page,true);

		xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
		
		xhr.send("");
	//}
}