JS Ajax 调用代码：

$.ajax({
    url: "/AjaxController/GetInfoById",
    type: 'GET',
    datatype: "json",
    contentType: "application/json; charset=utf-8",
    data: { id: id },
    success: function (data) {
        if (data) {
            alert(data.Id);
            alert(data.Title);
        }
    },
    error: function (error) {
        $("#result_div").html(error.responseText);
    }
});

Controller Action 代码：

[HttpGet]
public async Task<JsonResult> GetInfoById(int id)
{
    var result = await service.GetInfoById(id);
    return Json(result);
}

注意这种实现在 ASP.NET 5 项目中，是没有任何问题的，但在 ASP.NET MVC 5 中，会报如下错误：

This request has been blocked because sensitive information could be disclosed to third party web sites when this is used in a GET request. To allow GET requests, set JsonRequestBehavior to AllowGet.

正确代码（AllowGet）：

[HttpGet]
public async Task<JsonResult> GetInfoById(int id)
{
    var result = await service.GetInfoById(id);
    return Json(result, JsonRequestBehavior.AllowGet);
}

参考：

• What 'sensitive information' could be disclosed when setting JsonRequestBehavior to AllowGet
• JSON Problem - JsonRequestBehavior to AllowGet.
• JsonResult作为Action返回值时的错误