$('.js-submit').on('click',function(e){
    e.preventDefault();
    var thisForm = $(this).closest('.contentForm');
    var formAction = thisForm.attr('data-action');
    var formMethod = thisForm.attr('data-method');

    var data = thisForm.find("input,select,textarea").serialize()

    $.ajax({
        type: formMethod,
        url: formAction,
        data: data,
        success: function() {
            console.log('success!'); // or not!
        },
        error:function (xhr, ajaxOptions, thrownError){
            console.log(xhr.status); // 0
            console.log(thrownError); // empty
        }
    });
});