JavaScript tree functionality without framework

I'd like to display a tree on a Facebook page with JavaScript. Therefore there can be no dependencies on frameworks such as jQuery or Ext which won't run on Facebook, at least as far as I know when I last worked on that platform (April 2009). Can anybody recommend a "framework-free" JavaScript/tree library? I have ported some fairly complex JavaScript to Facebook so I'm sure I'll be able to port just about any existing pure JavaScript library.

Clarification points:

• I am targeting FBJS
• I too can (and did) google for JavaScript/tree engines but am seeking recommendations as to which one(s)

Look at this implementation... http://www.destroydrop.com/javascripts/tree/