React proposes a simple declarative way to build an application’s view. It’s straightforward to write a hierarchy of stateless components or to change a state synchronously. The whole app works as an integration of two pure functions “state(event)” and “view(state)“. The behavior is testable and predictable. But you can’t make something complex without depending on an external data sources integration: side effects come into the stage. Beware, you’re approaching the Dark Zone of functional programming now :)
