How to show confirm box on textChanged event of text box in ItemTemplate of gridview

[md1006]

I've used textbox in ItemTemplate of gridview. I need a confirm box on textChanged event of the respective text box. If user confirms as Ok/Yes then continue with some code else if user clicks on Cancel/No then do some other action.
I've tried using:

  Page page = HttpContext.Current.Handler as Page;
                    ScriptManager.RegisterClientScriptBlock(page, page.GetType(), "key2", "confirm('Do you want to update?');", true);

But I was not able to achieve desired output.
Plz' Help me with this code.

[Frinavale]

To prevent a postback to the server return False to the client-side (JavaScript) "onclick" event.

Try this:

 Page page = HttpContext.Current.Handler as Page;
                    ScriptManager.RegisterClientScriptBlock(page, page.GetType(), "key2", "return confirm('Do you want to update?');", true);

-Frinny