Mastering Immutable.js

Side-effects

The other thing we'll want to pass to the App() function are the side-effect functions. The aim is to pass the side-effect functions that handle one slice of the overall application state. There's little point in having a side-effect function that runs in response to every conceivable state change. In fact, we can map side-effect functions in the same way as we do with the state itself:

App(  Map.of(    'home', Map.of(...),    'users', Map.of(...),    'settings', Map.of(...)  ),  Map.of(    'home', (home) => { ... },    'users', (users) => { ... },    'settings', (settings) => { ... }  ));

The map with the side-effect functions closely resembles the application state map. This allows us to run certain behavior when a certain part of the state changes. ...