Redux Notes

Principles of redux

Use pure functions (those which rely only upon the input args, do not mutate the input args and do not do anything else such as make a database call)

State is kept in a single store

State is read-only and can only be changed by actions

Actions

Actions are objects which send data to the store. They are sent there using store.dispatch(). There is no other way of getting data to the store.

They must include a ‘type’ e.g. ‘ADD_TODO’.

Pass as little data in each action as possible (single responsibility!)

Action creators create the actions. All they do is return the action! Use the dispatch function to dispatch them.

Reducers

Reducers describe how the state is updated in response to actions. It must be pure. That means it should not mutate arguments, call APIs or call non-pure functions. It just returns the new state.

Stores

Stores store the state of the application. In redux a single store is used. Reducer composition can be used to split data handling logic.

getState() allows access to state dispatch(action) lets state be updated subscribe(listener) registers listeners and returns a function to unsubscribe listeners

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