function check_input(){
   var message_alert = "";
   for(var i = 0; i < window.document.forms[0].length ; i++) {
      var rechRapide = window.document.forms[0].elements[i].value;
      var nom_champ = window.document.forms[0].elements[i].name;
      window.document.forms[0].elements[i].style.backgroundColor = "#FFFFFF";
      if(rechRapide == "") {
         window.document.forms[0].elements[i].focus();
         window.document.forms[0].elements[i].style.backgroundColor = "#CCCCCC";
         message_alert +=" Veuillez remplir le champ " + nom_champ +"\n";
      }
   }
   

   
   
   if (message_alert == "") {
         return true;
      } else {
         message_alert = "Informations omises dans le formulaire : \n" + message_alert;
         alert(message_alert);
         return false;
         }
}