Prevent multiple votes on Node/Express + Pusher JS Voting App

Question

I'm creating a simple voting app where by the client gets to choose from a HTML select dropdown and select an option, and then submitted through a form it fires a POST request to save the selection in the database. This is then updated on the front-end.

There is currently no authentication implemented, but I may pursue this if needed.

My main concerns are someone voting a ridiculous amount of times and also the fairness of been able to only vote once.

For now I've just added local storage when the client votes so when the app re-renders the select is disabled, obviously this isn't a solid solution as they can clear this/use another device.

I've never built a voting app before so I don't have experience in this situation, I was curious what the best solution was for something like this. It's not a serious app, but I would like to resolve this in a better way than using local storage if possible.

POST request

router.post('/allTime', async (req, res) => {
    try {
        const guest = await req.body.guest;
        
        if(guest) {
            const guestFormatted = guest.toLowerCase();
            const guestPoll = await new GuestPoll({
                guest: guestFormatted,
                points: 1
            }).save();

            pusher.trigger("poll", "poll-vote", {
                guest: guestPoll.guest,
                points: parseInt(guestPoll.points)
            });
        }
        
        return res.json({
            message: 'Vote submitted'
        })
    } catch(err) {
        return res.json({
            err
        });
    }
});

Answer 1

"Your only real options for limiting voting are to limit by ip address and/or by an authenticated account" is not true. Unique Device ID's exist.

How to allow only 1 vote per person(computer/mobile) on 1 post at website without making user accounts ?