Confirm postback after OnClientClick button

Question

how to confirm postback after onClientClick.

 

I want to display confirm message before removing record from gridview. I tryied meny thing but not yet get any solution.

 

here is my code

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<asp:Button ID="btnRemoveWishList" runat="server" CausesValidation="True" CssClass="btn-xs btn-info"

PostBackUrl='<%#"removeWishList.aspx?designNo=" + HttpUtility.UrlEncode(Eval("designNo").ToString())%>' Text="Remove From Wish List"></asp:Button>