All reducers will be invoked when an action is dispatched?

Question

I am using combineReducers to combine all the reducers to create the store, does it mean that any action dispatched from any view will trigger all the reducers being invoked

Answer 1

Yes, that is correct.

However one option you have to optimize this behaviour (suggested from the Redux docs) is to use 'reselect' https://github.com/rackt/reselect

Reselect basically allows you to create memoized selectors, whereby you can say that props A depends on state B and state C, and therefore only recompute props A if state B or state C changes.

Notice that this will still trigger all of the reducers to run (and go through the switch statement to see if the action might apply to them) - I believe there is no way around this behaviour. Using reselect however means that your top level component will only receive a prop/state change if there was an actual change that affects that state, rather than triggering a change every time and making React re-render everything, even when the change had no effect because it was somewhere unrelated. (The readme in reselect explains better)