https://www.iguides.ru/local/templates/iguides-2022/js/general.js?17897192912014

1document.addEventListener('DOMContentLoaded', () => {
2    const SCROLL_OFFSET = 3000;
3    const scrollTop = document.querySelector('._scroll-top');
4    scrollTop.addEventListener('click', () => {
5        document.body.scrollTop = 0;
6        document.documentElement.scrollTop = 0;
7    })
8    window.addEventListener('scroll', () => {
9        if (document.body.scrollTop > SCROLL_OFFSET || document.documentElement.scrollTop > SCROLL_OFFSET) {
10            scrollTop.classList.add('_active')
11            document.documentElement.classList.add('_has-scroll');
12        } else {
13            scrollTop.classList.remove('_active')
14            document.documentElement.classList.remove('_has-scroll');
15        }
16    })
17
18    // Высота футера-клона в css-переменной --footer-clone-height на <html>
19    let frame = null;
20    const setFooterHeight = () => {
21        const clone = document.querySelector('.i-footer_clone');
22        document.documentElement.style.setProperty('--footer-clone-height', `${clone ? clone.offsetHeight : 0}px`);
23    };
24    const updateFooterHeight = () => {
25        if (frame !== null) return;
26        frame = requestAnimationFrame(() => {
27            frame = null;
28            setFooterHeight();
29        });
30    };
31    const observeFooterClone = () => {
32        const clone = document.querySelector('.i-footer_clone');
33        if (!clone) return false;
34        if (window.ResizeObserver) {
35            new ResizeObserver(updateFooterHeight).observe(clone);
36        }
37        return true;
38    };
39
40    setFooterHeight();
41    window.addEventListener('resize', updateFooterHeight);
42
43    // клон попадает в body только после "показать ещё"
44    if (!observeFooterClone()) {
45        const watcher = new MutationObserver(() => {
46            if (!observeFooterClone()) return;
47            watcher.disconnect();
48            updateFooterHeight();
49        });
50        watcher.observe(document.body, { childList: true, subtree: true });
51    }
52})