Reducer, sans boilerplate

chat-reducer-sans-boilerplate.js

const chatReducer = (state = defaultState, action = {}) => {
  const { type, payload } = action;
  switch (type) {
    case ADD_CHAT:
      return Object.assign({}, state, {
        chatLog: state.chatLog.concat(payload)
      });

    // Catch all simple changes
    case CHANGE_STATUS:
    case CHANGE_USERNAME:
      return Object.assign({}, state, payload);

    default: return state;
  }
};