Question

I have a AjaxCall.aspx page that will be called another page by .ajax() using jquery.
At AjaxCall.aspx I had remove all the html tag and left only

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="AjaxCall.aspx.cs" Inherits="_AjaxCall" %>

and at the code behind it was a simple on the pageload event.

protected void Page_Load(object sender, EventArgs e)
{
    Response.write("{ \"Testing\": \"Hello World!\" }");
}

I monitor the ajax request in Chrome developer tools in Network and I notice that every time I make a ajax request to AjaxCall.aspx page, it requested twice in a row. I later went into debug mode to check and discover that the pageload event fired twice.
I did some digging and found that an empty img src has something to do with this, but the problem is I have no any html tag in the AjaxCall.aspx page!

I later tried to add back the HTML body and form tag, and try to call that page again, and good news is it load once, but as soon as I add those html tag back to AjaxCall.aspx, it load twice again.

I can’t have those html tag at my AjaxCall.aspx because it suppose to return a json format data when it is requested, having those html tag will cause error on whatever page that called it. At the same time I don’t want it to continue load twice on every call I made. So is there anyway to overcome this problem?

Answer 1

If you want to deliver JSON response with application page (.aspx and code behind), you have to flush your response and close it in order to stop the process.

If you don’t do that, the page .aspx will be return, may be with some HTML tag generating multiple request (like img with bad src)

Try this:

protected void Page_Load(object sender, EventArgs e)
{
    Response.write("{ \"Testing\": \"Hello World!\" }");
    Response.Flush();
    Response.End();
}

Moreover, you can also use before your Response.write a Response.Clear in order to clear the optionnal content that could have been injected by any code, just to be sure to send only this content.