WebApi跨域設定：

        public static void Register(HttpConfiguration config)
        {
            //跨域設定
            config.EnableCors(new EnableCorsAttribute("*", "*", "*"));
            // Web API 配置和服務

            // Web API 路由
            config.MapHttpAttributeRoutes();

            config.Routes.MapHttpRoute(
                name: 
 
"DefaultApi",
                routeTemplate: "api/{controller}/{action}/{id}",
                defaults: new { id = RouteParameter.Optional }
            );

        }

ajax 呼叫方法：

    $("#tijiao").on("click", function () {
        var balance = {
            "SubCom_Code": $("#subcompany_in").val(),
            
 
"BooK_Id": $("#bookid_in").val(),
            "Card_Id": $("#cardid_in").val(),
            "Card_Address": $("#cardaddress_in").val(),
            "Book_UserId": $("#bookuser_in").val(),
            "Contents": $("#content_in").val()
        };
        $.ajax({
            url: URI.BalanceRegister.InsertBalance,
            dataType: 
 
'json',
            data: JSON.stringify(balance),
            type: 'POST',
            'Content-Type': 'application/json',
            success: function (response) {
                if (response.Code == 200) {
                    layer.alert('新增成功');
                }
                else {
                    layer.alert('新增失敗');
                }
            }
        });
    })