Can You Afford It? Real-World Web Performance Budgets(infrequently.org)

    JQueryEventObject) => {
        e.preventDefault();
        let $form = $(e.currentTarget);
        $.ajax({
            type: $form.attr("method"),
            url: $form.attr("action"),
            data: $form.serialize()
        })
        .done(() => {
            //do something
        })
        .fail((e) => {
            if (e.status == 400) {
                $(".js-form-wrapper").html(e.responseText);
                this.wireUpControls();
            } else {
                //handle error
            }
        })
    }

    $("#your-form").submit(this.onSubmit);