submit_message.js

document.body.addEventListener( 'click', function (event) {
    if( event.target.className === 'unique_class_name' ) {
        const form = event.target.form;
        const data = new FormData(form);

        const request = new XMLHttpRequest();
        request.open(form.method, form.action, true);
        request.send(data);

        // logFormData(data);
       
        request.addEventListener("load", function () {
            if (this.readyState === 4 && this.status === 200) {

                // catch JsonResponse from Django
                const response = JSON.parse(this.responseText);

                // display message
                const messages = document.getElementById("messages-list");
                messages.innerHTML += response.msg;
                fade_alerts();
            }
        });
    }

});