Use sweetAlert with Rails UJS.

sweetAlert-rails.js

$.rails.allowAction = function(link) {
  if ( ! link.attr('data-confirm') ) return true;
  $.rails.showConfirmDialog(link);
  return false;
};

$.rails.confirmed = function(link) {
  link.removeAttr('data-confirm');
  link.trigger('click.rails');
};

$.rails.showConfirmDialog = function(link) {
  sweetAlert({
    title: link.attr('data-confirm'),
    showCancelButton: true
  }, function(isConfirmed) {
    if (isConfirmed) $.rails.confirmed(link);
  });
};