timer on keycloak's auth page

auth_page_timer.user.js

// @match        https://*/auth/realms/myrealm/protocol/openid-connect/auth*

(function() {
    'use strict';
    var divDuration = document.createElement("div");
    divDuration.setAttribute('id', 'userscript_duration');
    document.getElementById('kc-header-wrapper').after(divDuration);
    const start = Date.now();
    function update_userscript_duration() {
        document.getElementById('userscript_duration').innerHTML = ((Date.now() - start) / 1000 / 60).toFixed(1);
        setTimeout(update_userscript_duration, 6000);
    }
    update_userscript_duration();
})();