<script>
    $(document).ready(function () {
        $("#order-form-submit").click(function () {
            var name=$("#name").val(),
                phone=$("#phone").val(),
                mail=$("#mail").val(),
                data=$('#data').val()
                fail="";
            if (name.length<3) fail="1111111ս";
            else if (phone="/374\d{8}/") fail="1111111";
            else if (mail.split ("@").length-1==0 || mail.split(".").length-1==0)
                fail="1111111";
            if (fail!=""){
                $("#messageShow").html(fail);
                $("#messageShow").show();
                return false;
            }
            $.ajax ({
                url: '/ajax/product-order-ajax.php'.,
                type: 'POST',
                cache: false,
                data:{'name': name, 'phone': phone, 'mail' : mail, 'data': data }
                dataType: 'html',
                success: function (data) {

                }
            })
        });
    });
</script>


вот сама форма
<form class="order-form"  action="product-order-code.php">
    <input class="order-form-name" type="text" id="name" placeholder="цсдф">
    <input class="order-form-phone" type="text" id="phone" placeholder="асдфгфдс">
    <input class="order-form-mail" type="text" id="mail" placeholder="сдфгфдсдфг">
    <input class="order-form-data" type="text"   id="data" value="<?php echo $dataname;?>" readonly>
    <div id="messageShow"></div>
    <input type="submit" id="order-form-submit" class="btn-submit" value="Заказать">
</form>