Function basicStateReducer

docs/external/js/react-dom.development.js:15146–15149

(state, action)

  }

  function basicStateReducer(state, action) {
    // $FlowFixMe: Flow doesn't like mixed types
    return typeof action === 'function' ? action(state) : action;
  }

  function mountReducer(reducer, initialArg, init) {
    var hook = mountWorkInProgressHook();