https://www.oxera.com/wp-content/plugins/facetwp-alpha/assets/js/front.js?ver=1.4

1(function($) {
2    $(function() {
3        FWP.hooks.addAction('facetwp/refresh/alpha', function($this, facet_name) {
4            FWP.facets[facet_name] = $this.find('.facetwp-alpha.selected').attr('data-id') || '';
5        });
6    });
7
8    $().on('click', '.facetwp-alpha.available', function() {
9        var $parent = $(this).closest('.facetwp-facet');
10        var is_selected = $(this).hasClass('selected');
11        var facet_name = $parent.attr('data-name');
12
13        $parent.find('.facetwp-alpha').removeClass('selected');
14
15        if (! is_selected) {
16            $(this).addClass('selected');
17        }
18
19        if ('' !== $(this).attr('data-id')) {
20            FWP.frozen_facets[facet_name] = 'soft';
21        }
22        FWP.refresh();
23    });
24})(fUtil);