Question

I’m creating a custom web control, basically extending RadTextBox since it doesn’t have onBlur() event. I added a script in the .ascx file. I am trying to register the script but it fails. I’m not sure what I’m missing here.

<script language="javascript">
    function handleLostFocus(o) {
        aler(o.toString());
    }
</script>

public partial class MyTextBox : RadTextBox, IScriptControl
{
    private void RegisterScripts()
    {
        try
        {
            String csname1 = "handleLostFocus";
            Type cstype = this.GetType();

            String cstext1 = "alert('Hello World');";
            ScriptManager.RegisterStartupScript(this, cstype, csname1, cstext1, true);
        }
        catch (Exception ex)
        {

        }
    }

    public MyTextBox()
    {
        Attributes.Add("padding", "5px");
        Skin = "Office2007";
        Attributes.Add("onBlur", "handleLostFocus(this);");

        RegisterScripts();
    }
}

Answer 1

You’re calling RegisterScripts in the constructor of your class. Your control is not yet in the Page in the constructor and hence you cannot register a startup script for a control that’s not even on the Page yet.

I suspect the best place to do this would be the Init method. You can do this by replacing the call in your constructor with this:

Init += (s,e) => { RegisterScripts(); };

(You could also create a full Init method on your control, but this is the short-hand version)