Parsley + recaptcha v3 promise

I’m not able to get the following code to work:

$(function() {
    function verifyRecaptcha() {
        return new Promise((resolve, reject) => {
            grecaptcha.execute('RECAPTCHA_SITE_KEY', {action: 'submit'}).then(function(token) {
                postJson('frontend/verify_recaptcha/'+token, null, function(d) {
                    if (d.pass) {
                        resolve('Verified');
                    } else {
                        reject('Not verified');
                    }
                });
            });
        });
    };

    var parsleyForm = $('#enquiry-form').parsley().on('form:submit', function(formInstance) {
        var validationResult = false;

        verifyRecaptcha().then(function() {
            console.log('VERIFIED');
            validationResult = true
        }).catch(function() {
            console.log('NOT VERIFIED');
            validationResult = false;
        });

        console.log('Resultat: '+validationResult);

        return validationResult;
    });
});

I already tried a lot with await/async, but it always submits the form.

I think I cannot be the only one who needs to implement Parsley with recaptcha v3? Any ideas? 🙂