https://www.corelp.co.uk/wp-content/themes/core-lp/includes/js/upsell-popout.js

1function closeUpsells() {
2    document.body.classList.add("show_upsells_close");
3    setTimeout(function(){
4        document.body.classList.remove("show_upsells_close");
5        document.body.classList.remove("upsells_open");
6    },300);
7    document.body.classList.add("upsells_closed");
8}
9function openBasket() {
10    document.body.classList.add("upsells_open");
11}
12var quantity = document.querySelectorAll('#upsell_popout .button_container .input-text');
13quantity.forEach( (input) => {
14    input.addEventListener('change', function () {
15        input.nextElementSibling.setAttribute('data-quantity', input.value);
16    })
17});
18jQuery(document.body).on('removed_from_cart updated_cart_totals', function () {
19    $(document.body).trigger('wc_fragment_refresh');
20});