Actually, IIRC it's the exact same reason as the io.js split. The maintainer of jsdom had changes that weren't being merged into node's VM module.
So jsdom 3.x used a lib called "contextify". When io.js was released and the changes included, node support was dropped. Now node 4.0.0 is out and has those changes, jsdom now works on node again.
So jsdom 3.x used a lib called "contextify". When io.js was released and the changes included, node support was dropped. Now node 4.0.0 is out and has those changes, jsdom now works on node again.