Science Knowings: JavaScript Course For Social Media

Code Splitting

Code Splitting

Lazy Loading was about loading code when it's needed, but Code Splitting divides your JavaScript bundle into smaller units, loading only what's necessary on-demand. This amazing technique can significantly improve application performance!

Benefits of Code Splitting

  • Faster initial page load
  • Improved user experience
  • Reduced bundle size
  • Better cache utilization
  • Easier maintenance and code reusability

Dynamic Import() Function

The import() function is a way to dynamically import code. It returns a Promise that resolves to the imported module. This allows you to load code on-demand, only when it's needed.

Webpack Code Splitting

Webpack provides built-in support for code splitting. You can use the import() function or the splitChunks plugin to split your code into smaller chunks.

Example: Splitting a Header Component

Let's say we have a Header component that we want to load only when the user scrolls to the top of the page:

import React, { lazy } from 'react'; const Header = lazy(() => import('./Header')); const App = () => { const [showHeader, setShowHeader] = React.useState(false); const handleScroll = () => { if (window.scrollY > 100) { setShowHeader(true); } }; React.useEffect(() => { window.addEventListener('scroll', handleScroll); return () => { window.removeEventListener('scroll', handleScroll); }; }, []); return (
{showHeader &&
); }; export default App;

Lazy-Loading vs. Code Splitting

Lazy-loading is a technique that delays loading of non-critical resources until they are needed. Code splitting, on the other hand, divides your code into smaller units that can be loaded independently.

Best Practices for Code Splitting

  • Split code by feature, not by file
  • Keep chunks small and avoid over-splitting
  • Use a code splitting strategy that fits your application
  • Monitor and adjust your code splitting strategy as needed

Tips for Effective Code Splitting

  • Use a code analyzer to identify unused code
  • Consider using a lazy-loading library
  • Experiment with different code splitting strategies
  • Monitor your application's performance

Code Splitting and Webpack Chunks

Webpack generates chunks when it bundles your code. Code splitting allows you to control how these chunks are generated, giving you more flexibility over how your application is loaded.

Example: Code Splitting with React Suspense

React Suspense allows you to handle the loading state of code-split components gracefully. You can show a loading indicator while the component is loading, and then render the component when it's ready.

Code Splitting for Improved Performance

  • Reduces page load time
  • Improves user experience
  • Makes your application more scalable
  • Can improve SEO

Code Splitting vs. Server-Side Rendering (SSR)

SSR is a technique that renders your application on the server before sending it to the client. This can improve performance, but it can also make your application less flexible. Code splitting, on the other hand, allows you to achieve good performance without the drawbacks of SSR.

Real-World Code Splitting Examples

  • React Router
  • Redux
  • Webpack
  • Create React App

Next Topic: Tree Shaking

In the next session, we'll explore Tree Shaking, a technique to eliminate unused code from your JavaScript bundle. Follow us to learn more and optimize your code for better performance!