Asp.Net Service method Is Not Executing or Calling Inner Method or Statement on BeforeUnload event-CodePudding

I have beforeunload event in js which will hit the .asmx service method as provided below.

.js event

$(window).on("beforeunload", function () {            
        var d, str;
        str = '{Id:"'   $('#hdnId').val()   '"}';
        d = str;

        $.ajax({
            type: "POST", //GET or POST or PUT or DELETE verb
            url: "../POC.asmx/fUpdateTimeInterval",
            data: d,
            contentType: "application/json; charset=utf-8",
            dataType: "json", //Expected data format from server
            async: true,
            beforeSend: function () {
                //  BlockUI();
            },
            success: function (data, Type, xhr) {//On Successfull service call

            },
            error: function (XMLHttpRequest, textStatus, errorThrown) {
                alert(errorThrown);
            },
            complete: function () {

            },
            failure: function () {

            }
        });
    });

.asmx (Web Service)

[WebMethod(true)]
        public int fUpdateTimeInterval(String Id)
        { 
            return new MY_POC.DLL.Survey().fUpdateTimeInterval(Id);
        }

The above service will then call the below mentioned method defined in DLL class file.

public int fUpdateTimeInterval(Int32 Id)
        {

            List<SqlParameter> objParam = new List<SqlParameter>()
            {
                new SqlParameter{ParameterName ="@Id",Direction=ParameterDirection.Input,DbType=DbType.Int32,Value= Id},
            };

            MY_POC.DLL.SqlHelper.ExecuteNonQuery("MY_UpdateTimeInterval", System.Data.CommandType.StoredProcedure, objParam.ToArray());

            return 0;
        }

Now problem is when the page gets load on browser for first time I am getting current auto ID of the inserted row. If I refreshes the browser, then beforeunload event gets fired and update the row of received ID only. But if I close the tab or browser then the compiler would hit the service method and stops after opening brace, it does not executing further & not even showing any error.

After execution stops, I am getting the following message at Output screen of vs, but not showing any error.

CodePudding user response：

It sounds like execution of the request is being aborted because the browser is closing the connection.

You should consider using the Beacon API. It's well supported by almost all browsers and it's made for this purpose. From Mozilla's documentation:

The main use case for the Beacon API is to send analytics such as client-side events or session data to the server. Historically, websites have used XMLHttpRequest for this, but browsers do not guarantee to send these asynchronous requests in some circumstances (for example, if the page is about to be unloaded). To combat this, websites have resorted to various techniques, such as making the request synchronous, that have a bad effect on responsiveness. Because beacon requests are both asynchronous and guaranteed to be sent, they combine good performance characteristics and reliability.

You can also make your Ajax request synchronous to prevent the connection from closing but that will have an impact on your GUI as it will block until the request completes.