Enabling submit button only when all fields are valid

document.addEventListener('DOMContentLoaded', function(e) {
    const demoForm = document.getElementById('demoForm');

    // Get the submit button element
    const submitButton = demoForm.querySelector('[type="submit"]');

    FormValidation.formValidation(
        demoForm,
        {
            fields: {
                ...
            },
            plugins: {
                fieldStatus: new FormValidation.plugins.FieldStatus({
                    onStatusChanged: function(areFieldsValid) {
                        areFieldsValid
                            // Enable the submit button
                            // so user has a chance to submit the form again
                            ? submitButton.removeAttribute('disabled')
                            // Disable the submit button
                            : submitButton.setAttribute('disabled', 'disabled');
                    }
                }),
                ...
            },
        }
    );
});