Confirm Postback of a page from Client End

It is a very common issue to handle automatic postbacks to controls. Here I am going to explain how we can handle autopostback of a button click using Javascript Event.

Suppose you have a button :

<asp:button runat="server" onclick="btn_click" 
Id ="btnAutoPostBack" /> 

Now you want to occationally cancel the click event so that the page will only be posted back when you want. So add this code:

<asp:button runat="server" onclick="btn_click" 
Id ="btnAutoPostBack" onclientclick="javacript:return isValid();"/>

or Add the attribute onclick to the button in Page_Load :

btn.Attributes.Add("onclick", "javascript:return isValid()");

Now let us look what the function look like:

function isValid(){
   return confirm("Are you sure you want to postback?");
   //Returns true when click ok, otherwise false.
}

Thus when you click on Ok, the btn_click will get generated as the page is posted back, otherwise the page will remain intact.
here Javascript:return false; means we are disallowing the postback event of the button.