All objects in JavaScript are truthy per the spec, but in the DOM one non-primitive object is not. Which?

Question

There is this tweet on Twitter:

In JavaScript, all objects are truthy (as per the spec). In the DOM, there’s one exception to this rule. What is it? #

Answer 1

Just loop over the document and test all..

http://jsfiddle.net/UTNkW/3/

EDIT: Wrong test methodology, thankfully someone pointed it out and I could correct it.