Actions

Actions are plain objects describing what happened: `{ type: 'todos/toggle', payload: id }`. They are the public write API — serializable, loggable, replayable. Redux Toolkit `createSlice` generates action creators automatically.

					// RTK slice action
const todosSlice = createSlice({
  name: 'todos',
  initialState: [],
  reducers: {
    toggled(state, action) {
      const todo = state.find((t) => t.id === action.payload);
      if (todo) todo.done = !todo.done;
    },
  },
});
// dispatch(todosSlice.actions.toggled('t1'))
				

Action types should be namespaced (`feature/event`) to avoid collisions. Async workflows dispatch multiple actions: pending, fulfilled, rejected — or delegate to RTK Query endpoints.

The trade-off is explicit event history and debuggability versus ceremony for simple local updates.

On interviews: why actions are events, not imperative "setState" calls with hidden side effects.

Common pitfalls: non-serializable payloads (functions, promises), stringly-typed types without constants, and fat actions that carry entire server responses when normalization belongs in reducers.

Checklist:

• Serializable type + payload.
• Namespaced action types.
• createAction/createSlice for ergonomics.
• Separate intent (action) from transition (reducer).