Reducers

NgRx Reducers

• Pure functions
• Accept the current state and the action to be performed
• We can default the current state to an initial state

Example Reducer

export const userReducer(state = initialState, action: Action): State {
  switch (action.type) {
    case UserActions.AddUserSuccess {
      return {
        ...state,
        users: [
          ...state.users,
          action.user
        ]
      }
    }
    default:
      return state
  }
};

• We default the state argument to some initialState
• Reducer return type is State
• We do not mutate the state object
• Use spread operator to create shallow clone