[danield9tqh]

This does worry me a bit though. There is probably a reason they are difficult to test, because they go against the React DOM pattern of a component only having control over the DOM nodes inside it. Call me a purist but this seems like a deviation from React's functional roots and going against the very problem React was trying to solve in the first place.

[danabramov]

The feature is mostly intended for rendering into nodes not managed by React. Such as a document child that is sibling to the application root.

[maaaats]

That may be true, but not having this possibility has made react near unusable for a lot of common UI patterns on the web.