How to Call Server Side And Client Side function on Single Click of A Link Button

<asp:LinkButton ID="LinkButtonTest" runat="server" 
            OnClientClick="javascript:alert('Hi');" onclick="LinkButtonTest_Click">Testing

protected void LinkButtonTest_Click(object sender, EventArgs e){
            // code here.
}

__doPostBack('" + UniqueIDWithDollars(ctrl) + @"','');

linkbutton1.Attributes.Add("onclick", "javascript:return " +
   "confirm('Are you sure you want to delete this record " +
     DataBinder.Eval(e.Row.DataItem,"ID_OF_Record") + "')");

<asp:linkbutton id="lnkButton" runate="server" OnClick="lnkButton_Click" OnClientClick="return DisplayMessage();">Click Me!

function DisplayMessage()
{
    //message to be displayed to user goes here
    var response = true;//you can return false to prevent server-side code from being executed!
    return response;
}

protected void lnkButton_Click( object sender, EventArgs e )
{
   //whatever you want to do on server-side
}