reveal-on-focus.js

(function( $ ) {

    $.fn.revealOnFocus = function( userSettings ) {

        return $( this ).each(function() {
            var $this = $( this ),
                $target = $this.find('.reveal-on-focus_target'),
                $content = $this.find('.reveal-on-focus_content');

            $content.hide();

            $target.on('focus', function() {
                var duration = $.fn.expandable.calculateExpandDuration( $content.height() );
                $content.slideDown({
                    duration: duration,
                    easing: 'easeOutExpo'
                });
            });
        });

    };

  // Auto init
  $('.reveal-on-focus').revealOnFocus();

}(jQuery));