Also see Lin Clark's "React Fiber" talk, linked upthread. Basically, pieces of work can start and be interrupted, and then be restarted, which will mean that `componentWillMount` can be called several times before the component _actually_ mounts.
To be clear this is irrelevant to React 16 which works in sync mode for compatibility. We'll share more about any changes when we start enabling the async mode in Facebook products and figure out the best migration strategy.
- https://github.com/facebook/react/issues/7671
- https://twitter.com/dan_abramov/status/790590733468241920
- https://www.reddit.com/r/reactjs/comments/5fg7iq/why_should_...
- https://daveceddia.com/where-fetch-data-componentwillmount-v...
Also see Lin Clark's "React Fiber" talk, linked upthread. Basically, pieces of work can start and be interrupted, and then be restarted, which will mean that `componentWillMount` can be called several times before the component _actually_ mounts.