Question

I need read-access to a user-defined property of my UserControl, from within a <script> element. This script needs to run when the user clicks on the link (which I also don’t know how to setup). Thanks for your advice, SO!

Code-behind:

public partial class TNLink : System.Web.UI.UserControl
{
    [System.ComponentModel.BindableAttribute(true)]
    public virtual string TNImageURL { get; set; }

    [System.ComponentModel.BindableAttribute(true)]
    public virtual string FullImageURL { get; set; }

    [System.ComponentModel.BindableAttribute(true)]
    public virtual string Caption { get; set; }
}

ASP:

<script type="text/javascript">
    //****How do I access the FullImageURL property for this line?****
    document.getElementById('imgFull').src = FullImageURL;
</script>
<div style="text-align: center">
    <a>
        <asp:Image ID="imgTN" runat="server"
            ImageUrl='<%# DataBinder.Eval (Page, "TNImageURL") %>'
            style="border: 5px solid #000000; width: 85%;" /><br />
        <asp:Label ID="lblCaption" runat="server"
            Text='<%# DataBinder.Eval (Page, "Caption") %>' />
    </a>
</div>

Answer 1

As Franci wrote, you need to write the value of the property to your html output while constructing the page on the server.

This is probably the easiest way to do that with your example:

<script type="text/javascript">
    document.getElementById('imgFull').src = '<%= FullImageURL %>';
</script>

(The <%= %> construct is just short for Response.Write.)