so I've recently tried to create a booking site in which you can select a date you wish to book. Then you'd send a request to /api/v1/reserve which would check if the data is valid. Generate a stripe payment intent, save the reservation to the database and send the payment intent id to the front end (for confirmation). My problem is that if two clients click send at the same time, they both pay for the same date which shouldn't happen.

router.post("/reservation", async (req, res) => {

    //Check if everything is in the reqest
    if (!req.body?.name || !req.body?.phone || !req.body?.date) return res.sendStatus(400);
    if (!req.body.phone.match(/^[ ]{0,1}[4]{1,2}[8][\s0-9]*$/)) return res.status(400).json({
        type: ErrorTypes.PHONE
    });


    //Validating date
    const reservationDate = new Date(req.body.date);
    if (reservationDate < new Date()) return res.status(400).json({
        type: ErrorTypes.DATE
    });
    //Checking if date is already reserved
    if (await checkIfDateReserved(reservationDate)) return res.status(400).json({
        type: ErrorTypes.RESERVED
    })
    //if reservation date is weekend raise the price