__doPostBack is not defined

Question

Im getting that error when try to call a __doPostBack on one of my pages, every page that i have in the project use __doPostBack function but in this particular page im gett

Answer 1

__doPostBack() should be automatically included by any ASP.NET WebControl that could cause a post back. You sound like you are calling it manually in some Javascript you wrote. If so, you will need to include a WebControl, to make sure that function in inserted onto the page.

Answer 2

I had this problem when I wrote my own page code and forgot to put runat="server" on the form element.

Answer 3

I know it's been a while since this thread was active, but I'll add another tidbit for those coming along in the future.

The ClientScriptManager class has available a couple of methods that make dealing with JavaScript postbacks better. In particular is the GetPostBackClientHyperlink routine. It retuns a string that you can then just assign to the element's onclick client-side event. Any time you use this method the __doPostBack routine and any necessary hidden form fields are automatically generated, plus you don't have to write the JavaScript yourself. For example, I have this in the Page_Load:

lnkDeactivate.Attributes("onclick") = ClientScript.GetPostbackClientHyperlink(lnkDeactivate, "deactivate")

In this case, ClientScript is the ClientScriptManager object instance automatically made available by the page...I did not instantiate it. On the post-back, I use this code to detect the event:

If Not String.IsNullOrEmpty(Request("__EVENTARGUMENT")) AndAlso Request("__EVENTARGUMENT") = "deactivate") Then
  '-- do somthing
End If

I'm sure there are better/cleaner ways to hook this up, but I hope you get the idea behind it.

Answer 4

Try calling the RegisterRequiresPostBack method. It should make the ASP.NET runtime include the __doPostBack code.

Answer 5

 this.Page.ClientScript.GetPostBackEventReference(<a control>, string.Empty); 

This trick worked for me. Still would have liked to know why it wasn't rendering...

Thank you!

Answer 6

Here's why this was happening to me: I accidentally forgot that script tags must always have closing tags:

<script src="/Scripts/appLogic/Regions.js" />

I corrected the script tag:

<script src="/Scripts/appLogic/Regions.js" type="text/javascript" ></script>

and sanity returned.