function getXhr(){
	var xhr;
	if(window.XMLHttpRequest || window.ActiveXObject){
		if(window.XMLHttpRequest){
			xhr=new XMLHttpRequest();
		}
		else{
			try{
				xhr=new ActiveXObject("Msxml2.XMLHTTP");
			}
			catch(e){
				xhr=new ActiveXObject("Microsoft.XMLHTTP");
			}
		}
	}
	else{
		alert("Votre navigateur ne supporte pas l'objet XMLHttpRequest...");
		return null;
	}
	return xhr;
}