I'm using the Google Calendar API and can't figure out how to keep the user logged in when they refresh the page. I can't find anything online about this. If anyone could help, it'd be greatly appreciated! This is my current code to login the user:

function handleAuthClick() {
    tokenClient.callback = async (resp) => {
        if (resp.error !== undefined) {
            throw (resp);
        }
        await listUpcomingEvents();
    };

    if (gapi.client.getToken() === null) {
        tokenClient.requestAccessToken({prompt: 'consent'});
    } else {
        tokenClient.requestAccessToken({prompt: ''});
    }
}

My body element automatically runs this on load. I'm using this guide: https://developers.google.com/calendar/api/quickstart/js.