Pure Logics and Side Effects

So pure logic is something that i showed you with counter example where you can increase, decrease or reset the counter. But you might see that this is trivial to lift such pure functions into RxJS. Side-effects are actually what RxJS shine at.

const refetch = () => ajax.get('/todos')

Actually, you don't have to reimplement such pure functions or lift them to RxJS space. For example, you have a component called <TodoList />. What you can do to avoid reimplementing all the logics is to lift the state up:

<TodoList todos={todos} onStateChange={onStateChange} />

And wrap it inside a subscription:

<Subscribe observer={todos$}>
  {todos => <TodoList todos={todos} onChange={onStateChange} />}
</Subscribe>

Then, you can have a common routine for pure logics:

onStateChange(todos) {
  todos$.next(todos)
}

And seperate routines for side-effects to take place:

const refetchTodos$ = new Subject()
refetchTodos$
  .pipe(switchMap(() => ajax.get('/todos')))
  .subscribe(todos$)

const refetchTodos = bindAction(refetchTodos$)