asp.net - Find out client-side ID of HTML element created by .NET?

Question

How do I write some client-side script to access a HTML element when .NET has generated the element's ID at runtime?

At present I have this in my ASPX:

<asp:Content ContentPlaceHolderID="middle_area" runat="server">
    <asp:Image ID="ImageBarChart" runat="server" />
</asp:Content>

<script>
var oImage = document.getElementById('ctl00_middle_area_ImageBarChart')
</script>

It it working at present, but I doubt it is reliable!

Answer 1

ClientID: Documentation

You would then do <%= ImageBarChart.ClientID %> to put it in your javascript