nextcloud/php/public/automatic_reload.js

window.addEventListener("load", function(event) {
    if (document.hasFocus()) {
        // hide reload button if the site reloads automatically
        let list = document.getElementsByClassName("reload button");
        for (let i = 0; i < list.length; i++) {
            // list[i] is a node with the desired class name
            list[i].style.display = 'none';
        }

        // set timeout for reload
        setTimeout(function(){
        window.location.reload(true);
        }, 5000);
    } else {
        window.addEventListener("beforeunload", function() {
            document.getElementById('overlay').classList.add('loading')
        });
    }
});