// State export type UserStateType = { ourNumber: string; }; // Actions type UserChangedActionType = { type: 'USER_CHANGED'; payload: { ourNumber: string; ourPrimary: string; }; }; export type UserActionType = UserChangedActionType; // Action Creators export const actions = { userChanged, }; function userChanged(attributes: { ourNumber: string; ourPrimary: string }): UserChangedActionType { return { type: 'USER_CHANGED', payload: attributes, }; } // Reducer function getEmptyState(): UserStateType { return { ourNumber: 'missing', }; } export function reducer(state: UserStateType, action: UserActionType): UserStateType { if (!state) { return getEmptyState(); } if (action.type === 'USER_CHANGED') { const { payload } = action; return { ...state, ...payload, }; } return state; }