network-resurrector-frontend/src/state/reducer.js

export function reducer(state, action) {
  switch (action.type) {
    case "onCredentialsChange": {
      const { prop, value } = action.payload;
      return {
        ...state,
        credentials: {
          ...state.credentials,
          [prop]: value
        }
      };
    }
    default: {
      return state;
    }
  }
}

export const dispatchActions = dispatch => ({
  onCredentialsChange: (prop, value) =>
    dispatch({ type: "onCredentialsChange", payload: { prop, value } })
});