https://www.arantxa-coca.com/js/broccoli-fold-unfold-infobox.js

1$( function() {
2	$('.fold-unfold-infobox').each( function() {
3		var TRANS_DURATION = 300;
4		var infobox = $(this);
5		var visible_part = infobox.find('.visible-part');
6		var hidden_part = infobox.find('.hidden-part');
7		var button = infobox.find('.toggle-button');
8		button.on('click', function() {
9			hidden_part.slideToggle(TRANS_DURATION, function() {
10				if(hidden_part.is(':visible')) {
11					infobox.addClass('unfolded');
12				} else {
13					infobox.removeClass('unfolded');
14				}
15			});
16		});
17		hidden_part.hide();
18	});
19});