I kept some places intact (search for @jsx) because they require other bigger changes:
- ref-01-top-level-api.md
- grunt/tasks/npm.js
- old blog posts (don't change those)
- examples/ folder, as they have their own package.json that rely on old dependencies (node-jsx, reactify) that haven't upgraded to 0.12
The reason I chose to submit this is because it was initially unclear from the docs that the transition group needed to already be mounted in order for it to work properly.
When I first read these docs, it was not immediately clear to me that I could
use `React.addons.CSSTransitionGroup` to animate a single item coming into view,
or an item replacing an item already there. This was partly due to the example
which rendered a list of items.
This PR adds a blurb about being able to use
`React.addons.CSSTransitionGroup` with one or zero items, provides a code
example, and adds a note blockquote that a `key` attribute must always be
provided on each child of `React.addons.CSSTransitionGroup`. The latter point
was not immediately obvious from the original `TodoList` code example, since it
renders a list which would normally require `key` attributes anyway.
Test Plan:
- Refreshed `http://localhost:4000/react/docs/animation.html`, saw that the
docs additions rendered correctly.
- Example code not tested (it was extracted from working code).
- Overview of add-ons for the add-ons page.
- Better title for `ReactLink`.
- Nicer code format for classSet example.
- Better explanation for `classSet`.