ReactJS - How to properly handle dynamic imports in a component to avoid unnecessary re-renders?
I'm trying to implement I'm writing unit tests and Could someone explain I've been banging my head against this for hours... I'm using React 17 with React Router for a single-page application. I've implemented dynamic imports using React.lazy and Suspense to load components on demand, but I'm facing unexpected re-renders whenever I switch routes. The component that I'm importing dynamically seems to re-render every time, which negatively impacts performance, especially since some of these components fetch data on mount. Here’s a simplified version of what I have: ```javascript import React, { Suspense, useEffect } from 'react'; import { BrowserRouter as Router, Route, Switch } from 'react-router-dom'; const LazyComponent = React.lazy(() => import('./LazyComponent')); const App = () => { return ( <Router> <Suspense fallback={<div>Loading...</div>}> <Switch> <Route path="/lazy" component={LazyComponent} /> {/* other routes */} </Switch> </Suspense> </Router> ); }; export default App; ``` In `LazyComponent`, I’m fetching some data from an API inside a `useEffect`: ```javascript import React, { useEffect, useState } from 'react'; const LazyComponent = () => { const [data, setData] = useState(null); useEffect(() => { const fetchData = async () => { const response = await fetch('https://api.example.com/data'); const result = await response.json(); setData(result); }; fetchData(); }, []); return <div>{data ? JSON.stringify(data) : 'Loading data...'}</div>; }; export default LazyComponent; ``` Every time I navigate away from `/lazy` and back, it seems to re-fetch the data, which I expected would be cached due to the empty dependency array in `useEffect`. Is there a way to persist the data or avoid the unnecessary re-rendering of `LazyComponent`? I've also attempted wrapping the `LazyComponent` in `React.memo`, but it didn't help. Any insights would be greatly appreciated! What am I doing wrong? Is this even possible? I'm working with Javascript in a Docker container on Linux.