reactjs - 更新 redux 存储时应用程序重新呈现

Question

每次我发送一个 Action 并更新我的商店时，我的整个应用程序都会重新呈现。我假设我的 connect/mapDispatchToProps 函数做错了什么？将 { ...actions } 作为第二个参数传递给我的 App.js 中的 connect 函数是否正确？

这是我的代码:

class App extends Component {
  componentDidMount() {
    this.props.fetchPages(api.API_PAGES);
    this.props.fetchPosts(api.API_POSTS);

    window.addEventListener('resize', () => {
      this.props.resizeScreen(window.innerWidth);
    });
  }

  render() {
    return (
      <div>
        {this.props.app.showIntro && <Intro {...this.props} endIntro={this.props.endIntro} />}

        {!this.props.pages.isFetching && this.props.pages.data &&
          <div>
            <Navbar {...this.props} />

            <Layout {...this.props}>
              <Switch location={this.props.location}>
                <Route
                  path={routes.HOME}
                  exact
                  component={() => (
                    <Home {...this.props} />
                  )}
                />
                <Route
                  path={routes.ABOUT}
                  component={() => (
                    <About {...this.props} />
                  )}
                />
                <Route
                  path={routes.NEWS}
                  exact
                  component={() => (
                    <News {...this.props} />
                  )}
                />
                <Route
                  component={NotFound}
                />
              </Switch>
            </Layout>
          </div>
        }
      </div>
    );
  }
}

function mapStateToProps(state) {
  return {
    app: state.app,
    pages: state.pages,
    posts: state.posts
  };
}

export default withRouter(connect(
  mapStateToProps,
  { ...actions }
)(App));

Action /index.js

export function resizeScreen(screenWidth) {
  return {
    type: types.RESIZE_SCREEN,
    screenWidth
  };
}

export function endIntro() {
  return {
    type: types.END_INTRO,
    showIntro: false
  };
}

export function toggleNav(bool) {
  return {
    type: types.TOGGLE_NAV,
    navOpen: bool
  };
}

export function toggleVideoPlayer(bool) {
  return {
    type: types.TOGGLE_VIDEO_PLAYER,
    videoIsPlaying: bool
  };
}

export function toggleScroll(bool) {
  return {
    type: types.TOGGLE_SROLL,
    disableScroll: bool
  };
}


// pages

function requestPages() {
  return {
    type: types.REQUEST_PAGES
  };
}

function receivePages(data) {
  return {
    type: types.RECEIVE_PAGES,
    data
  };
}


// posts

function requestPosts() {
  return {
    type: types.REQUEST_POSTS
  };
}

function receivePosts(data) {
  return {
    type: types.RECEIVE_POSTS,
    data
  };
}


// creators

export function fetchPages(path) {
  return (dispatch, getState) => {

    const { pages } = getState();

    if (pages.isFetching) return;

    dispatch(requestPages());
    fetch(`${process.env.API_URL}${path}`)
      .then(response => response.json())
      .then(json => dispatch(receivePages(json)));
  };
}

export function fetchPosts(path) {
  return (dispatch, getState) => {

    const { posts } = getState();

    if (posts.isFetching) return;

    dispatch(requestPosts());
    fetch(`${process.env.API_URL}${path}`)
      .then(response => response.json())
      .then(json => dispatch(receivePosts(json)));
  };
}

reducers/app.js:

const initialState = {
  screenWidth: typeof window === 'object' ? window.innerWidth : null,
  showIntro: true,
  navOpen: false,
  videoIsPlaying: false,
  disableScroll: false
};

export default function app(state = initialState, action) {
  switch (action.type) {

    case RESIZE_SCREEN: {
      return {
        ...state,
        screenWidth: action.screenWidth
      };
    }

    case TOGGLE_NAV: {
      return {
        ...state,
        navOpen: !state.navOpen
      };
    }

    case END_INTRO: {
      return {
        ...state,
        showIntro: false
      };
    }

    case TOGGLE_VIDEO_PLAYER: {
      return {
        ...state,
        videoIsPlaying: !state.videoIsPlaying
      };
    }

    case TOGGLE_SCROLL: {
      return {
        ...state,
        disableScroll: !state.disableScroll
      };
    }

    default: {
      return state;
    }
  }
}

reducers/posts.js 类似于 reducers/pages.js:

const initialState = {
  isFetching: false
};

export default function posts(state = initialState, action) {
  switch (action.type) {

    case REQUEST_POSTS: {
      return {
        ...state,
        isFetching: true
      };
    }

    case RECEIVE_POSTS: {
      return {
        ...state,
        isFetching: false,
        data: action.data
      };
    }

    default: {
      return state;
    }
  }
}

Answer 1

如果您遇到每次 redux 更新都会重新渲染太多应用程序的问题，使用更多连接组件并限制传递给每个组件的状态量会有所帮助。我看到您将 props 分散到每个页面中，这很方便，但却是重新渲染效率低下的常见原因。

<Home  {...this.props} />
<About {...this.props} />
<News  {...this.props} />

这可能会导致过多的数据被传递到这些组件中的每一个，并且每个 redux 操作都会导致整个页面重新呈现。

我看到的另一个潜在问题是您使用内联匿名函数作为路由的组件回调

<Route
    path={routes.ABOUT}
    component={() => (
        <About {...this.props} />
    )}
/>

我不确定 React Router 在这里是如何工作的，但一个潜在的问题是每次路由器重新渲染时，这些匿名函数都会再次创建全新的。 React 会将它们视为新组件并强制重新渲染。您可以通过使每个组件成为一个连接的组件来解决这个问题，这些组件会引入自己的 Prop ，然后像这样更新路由器

<Route
    path={routes.ABOUT}
    component={ConnectedAbout}
/>