Question

Here’s the button.

<asp:Button ID="_btnSearch" Text="Search" onclientclick="return CheckForEmptySearchBox(this.ClientID)" />

And here’s the Javascript function

<script type = "text/javascript">
        function CheckForEmptySearchBox(id) {
           alert("The ID of the button is: " + id)

           return false;
        }
</script>

I’m getting a alert box, saying “The ID of the button is: undefined“

Thanks for helping

Answer 1

It’s not ClientId, thats an server-side property use this.id.

<asp:Button ID="_btnSearch" Text="Search" onclientclick="return CheckForEmptySearchBox(this.id)" />

ClientId is used to get the client-side id thats generated by ASP.Net and use it server-side.