fetch("https://just-start.eu/api/index.php", {
        method: 'POST', // *GET, POST, PUT, DELETE, etc.
        mode: 'no-cors', // no-cors, cors, *same-origin
        cache: 'no-cache', // *default, no-cache, reload, force-cache, only-if-cached
        credentials: 'same-origin', // include, *same-origin, omit
        headers: {
            'Content-Type': 'application/json',
            // 'Content-Type': 'application/x-www-form-urlencoded',
        },
        redirect: 'follow', // manual, *follow, error
        referrer: 'no-referrer', // no-referrer, *client
        body: JSON.stringify({request: 'registerUser', authrequired: 'false', username: gebNaam, password: wachtwoord, fullname: volNaam, email: email}) // body data type must match "Content-Type" header
    })
        .then((response) => {
            response.json().then((data) => {
                if(data['API_code']==='003') {
                    //Gebruiker is al geregistreerd!
                } else if(data['API_code']==='OK') {
                    //Ga door!
                }
            });
        });