Event.observe(window, 'load',  function(event) {
    Event.observe('endroit', 'change',  function(element)
    {
        var url = '/soiree-information-date.php?endroit='+ this.value;

        new Ajax.Request(url, {
            method: 'get',
            onSuccess: function(transport)
            {
                $('date').innerHTML = transport.responseText;
            }
        });
    });
});