https://firstline.com.ua/CMS/js/pwa-install.js

1let deferredPrompt;
2
3const isIos = () => {
4    const userAgent = window.navigator.userAgent.toLowerCase();
5    return /iphone|ipad|ipod/.test(userAgent);
6}
7const isInStandaloneMode = () => ('standalone' in window.navigator) && (window.navigator.standalone);
8window.addEventListener('load', function () {
9    if (isIos() && !isInStandaloneMode()) {
10        showInstallButton();
11    }
12    if (!isIos()) {
13        window.addEventListener('beforeinstallprompt', (event) => {
14            // Prevent the default prompt
15            event.preventDefault();
16            // Save the event for later use
17            deferredPrompt = event;
18            // Display your custom "Install App" button
19            showInstallButton();
20        });
21    }
22});
23function showInstallButton() {
24    const installButton = document.querySelector('.pwa-install');
25    const installButtonUninstall = document.querySelector('.pwa-uninstall');
26    installButton.style.display = 'none';
27    installButtonUninstall.style.display = 'block';
28}
29
30function install() {
31
32    if (deferredPrompt) {
33        deferredPrompt.prompt();
34        deferredPrompt.userChoice.then((choiceResult) => {
35            if (choiceResult.outcome === 'accepted') {
36                console.log('User accepted the install prompt');
37            } else {
38                console.log('User dismissed the install prompt');
39            }
40
41            deferredPrompt = null;
42        });
43    }else if (isIos()) {
44
45        var modal = document.getElementById("myModalPWA");
46        var span = document.querySelector("#myModalPWA .close");
47
48        modal.style.display = "block";
49        span.onclick = function() {
50            modal.style.display = "none";
51        }
52    }
53}