function Panier(id_transporteur){
  var xhr=getXhr();

  xhr.onreadystatechange=function(){
    if(xhr.readyState==4 && xhr.status==200){
      var docXML=xhr.responseXML;
      var reponse=docXML.getElementsByTagName('reponse');
      var total=reponse.item(0).getElementsByTagName('total').item(0).firstChild.data;

      document.getElementById('prix_total').innerHTML=total;
    }
  }

  xhr.open("POST","panier.php",true);
  xhr.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
  xhr.send("id_transporteur="+id_transporteur);
}