function goupdathyzt(sqid, zt) {

$.ajax({
async: false,
url: "http://localhost:17298/api/aaa/sss",
type: "get",
//必填
contentType: "application/json; charset=utf-8",

data: { "huo_id": 13, "huozhu_id": 7 },//必要
timeout: 5000,

//服务器段返回的对象包含name,data属性. 
success: function (result) {
alert(result.obj.huo_num);
},
error: function (jqXHR, textStatus, errorThrown) {
alert(textStatus);
}
});
}

 protected void Application_BeginRequest()
        {
            if (Request.Headers.AllKeys.Contains("Origin") && Request.HttpMethod == "OPTIONS")
            {
                Response.End();
            }
        }

<system.webServer>
    <httpProtocol>
      <!--跨域配置开始-->
      <customHeaders>
        <add name="Access-Control-Allow-Origin" value="*" />
        <!--支持全域名访问，不安全，部署后需要固定限制为客户端网址-->
        <add name="Access-Control-Allow-Methods" value="GET, POST, PUT, DELETE, OPTIONS" />
        <!--支持的http 动作-->
        <add name="Access-Control-Allow-Headers" value="Content-Type" /><!--//,X-Requested-With,token-->
        <!--响应头 请按照自己需求添加 这里新加了token这个headers-->
        <add name="Access-Control-Request-Methods" value="GET, POST, PUT, DELETE, OPTIONS" />
        <!--允许请求的http 动作-->
      </customHeaders>
      <!--跨域配置结束-->
    </httpProtocol>