stepper.js

$(document).on('click', '@stepper-up, @stepper-down', function() {
  var sender = $(this);
  var parent = sender.parents('@stepper');
  var target = parent.find('@stepper-input');
  var val = parseInt(target.val());

  if (sender.is('@stepper-up')) {
    val++;
  }
  else {
    val--;
  }

  target.val(val);
  parent.trigger('stepper:changed', val);
});