Trigger backspace to empty drupal date/hour field

gistfile1.js

for (var id in Drupal.settings.datePopup) {
   $('#'+id).bind('keyup', function(e){
     var code = (e.keyCode ? e.keyCode : e.which);
     if (code==46 || code==8) {
       $(this).val("");
     }
   })
}