jquery validate ajax submit form

when the jquery validation plugin is used for validating the form data, such as below:

html code:

<form method="post" action="" id="buy-form" novalidate="novalidate">

                    <table style="margin:35px 150px 0 150px;">

                        <tr>

                            <td class="info-title">预定版本<input type="hidden" name="versionName" id="versionName" value="" /></td>

                            <td class="info-content-version">免费版本</td>

                        </tr>

                        <tr>

                            <td class="info-title">联系人</td>

                            <td class="info-content"><p><input class="required" type="text" placeholder="请输入联系人姓名（必填）" style="width:330px;" name="name" id="applicants-name" /></p></td>

                        </tr>

                        <tr>

                            <td class="info-title">电话</td>

                            <td class="info-content"><input type="text" placeholder="座机区号" style="width:100px;" name="locationNo" id="locationNo" /> - <input type="text" placeholder="座机号码/手机号码（必填）" style="width:209px;" name="phone" id="phone" /></td>

                        </tr>

                        <tr>

                            <td class="info-title">邮箱</td>

                            <td class="info-content"><input type="text" placeholder="请输入联系人邮箱地址（必填）" style="width:330px;" name="email" id="email" /></td>

                        </tr>

                        <tr>

                            <td class="info-title">公司名称</td>

                            <td class="info-content"><input type="text" placeholder="请输入联系人公司名称（必填）" style="width:330px;" name="companyName" id="companyName" /></td>

                        </tr>

                    </table>

                </form>

js code:

var form = $("#buy-form");

        form.validate({

            errorElement: "span",

            rules: {

                "name": {

                    required: true

                },

                "phone": {

                    required: true

                },

                "email": {

                    required: true

                },

                "companyName": {

                    required: true

                }

            },

            messages: {

                "name": {

                    required: "请输入联系人姓名",

                },

                "phone": {

                    required: "请输入号码",

                },

                "email": {

                    required: "请输入邮箱地址",

                },

                "companyName": {

                    required: "请输入公司名称",

                }

            }

        });

ajax submit code:

        $(".submit").click(function(){

                                    

            var form = $("#buy-form");

            var $alertDialog = $("#alert-dialog");



            form.submit(function (event) { event.preventDefault();});//阻止在数据校验失败的情况下提交表单；绑定事件，但不触发；

            form.submit();//触发绑定事件；

            var validator = form.validate();

            if (validator.numberOfInvalids() <= 0) {//判断加入所有校验都通过后再做ajax提交；

                $.ajax({

                    url: "Home/SubmitPurchaseApplication",

                    data: $("#buy-form").serialize(),

                    type: "post",

                    async: false,

                    success: function (data) {

                        freeDialog.dialog("close");

                        $("#alert-title h3").text("购买成功！");

                        $("#alert-message p").text("您的购买申请已经提交，我们会尽快联系您");

                        ShowAlertDialog(); //异步提交后弹框提示；



                    },

                    error: function () {

                        freeDialog.dialog("close");

                        $("#alert-title h3").text("购买失败！");

                        $("#alert-message p").text("您的购买申请出现异常，请重新申请");

                        ShowAlertDialog();

                    }

                });

            }

        });