Question

I’m not sure what’s the issue that is causing that error message when I try debugging with Firebug. Everything looks good to me.

Current Issue:

$("#SlideList option:selected") is null

Select Box Code (abridged) :

<select id="SlideList" name="D1" style="width: 130px;"> 
  <option value = "Numbers.pdf" >Numbers</option>
 </select>
 <img src="Button.png" onclick="SlidePDFOpen()" />

Javascript:

function SlidePDFOpen() {
window.open($("#SlideList option:selected").val());
}

Answer 1

You are using a jquery selector but you don’t have jquery included in the page.
The error you are getting therefore makes sense as the page can’t find the function val().

At the very least with jquery you would get an empty string.