Calling manual AJAX functions in ASP.NET WebForms with postbacks

Question

I'm developing something similar to the system console, but which renders with simple HTML-page.

Here are the codes:

• ASPX MarkUp: http://ideone.com/XPIjb2
• CodeBehind: http://ideone.com/RqeZAq

Code is rather in test state and I don't want to mention about code-style etc... I know this problem.

I'm confused a little with the AJAX calls of my WebForms project. So let me to describe, what I'm trying to do:

• First of all, I'm catching a key event Enter, when user has finished entering the text into <textarea>.

• Then I'm reading the text secondly, which user has added and send it via XmlHttp object to this page (postback action, because I'm sending POST HTTP queries to the same web page)

• At the third action, I analyse the string data and render the response in consoleOutput finally by setting the response with the CheckGetData()/GetDirectories() methods in the CodeBehind.

But, finally nothing is happen... The most strangest things for me, are:

• If to view IsPostBack value when XmlHttp has sent GET query at debug time, it would be false, why? As by the definition of postback, it's a such type of recursive HTTP query to the same web page (making POST queries from the web page to itself)
• I have noticed that values are changing by viewing it with the debugger. Debugger describes values were edited by expanding the small menu in Visual Studio, but if to switch to the web page from the embedded internal IIS Server in Visual Studio - there wouldn't be any changes, why?

So, the final question is: why do it call a bug and how to fix it?

Answer 1

Not a direct answer, just a suggestion of how you can achieve.

Use an UpdatePanel. Here is how you can achieve(bare minimum; a bit hacky):

Script:

<script>
    function keyPressed(e) {
        var code;
        if (window.event) {
            //IE
            code = e.keyCode;
        }
        else {
            //other browsers
            code = e.which;
        }
        //check, for example, if the Enter key was pressed (code 13)
        if (code == 13) {
            //Enter key pressed
            document.getElementById("<%= btnPostback.ClientID %>").click();
        }
        else {
            //Another key pressed
        }
    }
</script>

aspx markup:

<textarea id="consoleBody" rows="30" cols="30" runat="server" onkeypress="javascript:keyPressed(event);" />

<asp:UpdatePanel runat="server" UpdateMode="Conditional">
    <Triggers>
        <asp:AsyncPostBackTrigger ControlID="btnPostback" EventName="Click" />
    </Triggers>
    <ContentTemplate>
        <label id="consoleOutput" runat="server" />
    </ContentTemplate>
</asp:UpdatePanel>

<asp:Button Text="Enter" Style="display: none;" runat="server" ID="btnPostback" OnClick="HandleCommand" />

Code-behind:

protected void HandleCommand(object sender, EventArgs e)
{
    SetPageData();
    CheckGetData(); 
}