React数据缓存指南：如何优化前端数据的获取和更新效率

import Cache from 'cache';

const dataCache = new Cache();

function fetchData(url) {
  if (dataCache.has(url)) {
    return Promise.resolve(dataCache.get(url));
  }

  return fetch(url)
    .then(response => response.json())
    .then(data => {
      dataCache.set(url, data);
      return data;
    });
}

fetchData('/api/data1')
  .then(data => console.log(data));

// 创建一个Context
const DataContext = React.createContext();

// 提供数据的组件
function DataProvider({ children }) {
  const [data, setData] = useState(null);

  useEffect(() => {
    fetch('/api/data')
      .then(response => response.json())
      .then(data => setData(data));
  }, []);

  return (
    <DataContext.Provider value={data}>
      {children}
    </DataContext.Provider>
  );
}

// 使用数据的组件
function DataConsumer() {
  const data = useContext(DataContext);

  if (data === null) {
    return <div>Loading...</div>;
  }

  return (
    <div>{data}</div>
  );
}

// 在应用程序中使用数据
function App() {
  return (
    <DataProvider>
      <DataConsumer />
    </DataProvider>
  );
}

ReactDOM.render(<App />, document.getElementById('root'));

import { createStore } from 'redux';

// 定义数据状态的reducers
function dataReducer(state = null, action) {
  switch (action.type) {
    case 'SET_DATA':
      return action.payload;
    default:
      return state;
  }
}

// 创建store
const store = createStore(dataReducer);

// 获取数据的动作
function fetchData() {
  return dispatch => {
    if (store.getState() !== null) {
      return;
    }

    fetch('/api/data')
      .then(response => response.json())
      .then(data => {
        dispatch({ type: 'SET_DATA', payload: data });
      });
  };
}

// 在应用程序中使用数据
store.dispatch(fetchData());

function App() {
  const data = store.getState();

  if (data === null) {
    return <div>Loading...</div>;
  }

  return (
    <div>{data}</div>
  );
}

ReactDOM.render(<App />, document.getElementById('root'));