In our chat application, we have four key components: , , and . However, only three of these components are used instantly on the initial page load: , and . The isn't directly visible, and may not even be rendered at all if the user won't even click on the in order to toggle the . This would mean that we unnecessarily added the module to our initial bundle, which potentially increased the loading time!

In order to solve this, we can dynamically import the component. Instead of statically importing it, we'll only import it when we want to show the . An easy way to dynamically import components in React is by using React Suspense. The component receives the component that should be dynamically loaded, which makes it possible for the component to render its contents faster by suspending the import of the module!

Instead of unnecessarily adding to the initial bundle, we can split it up into its own bundle and reduce the size of the initial bundle!

A smaller initial bundle size means a faster initial load: the user doesn't have to stare at a blank loading screen for as long. The component lets the user know that our application hasn't frozen: they simply need to wait a little while for the module to be processed and executed.

Asset                             Size         Chunks            Chunk Names
emoji-picker.bundle.js           1.48 KiB      1    [emitted]    emoji-picker
main.bundle.js                   1.33 MiB      main [emitted]    main
vendors~emoji-picker.bundle.js   171 KiB       2    [emitted]    vendors~emoji-picker

Whereas previously the initial bundle was , we've been able to reduce it to by suspending the import of the !

By dynamically importing the component, we managed to reduce the initial bundle size from to ! Although the user may still have to wait a while until the has been fully loaded, we have improved the user experience by making sure the application is rendered and interactive while the user waits for the component to load.

Server-side rendering doesn't support React Suspense (yet). A good alternative to React Suspense is the

loadable-components

library, which can be used in SSR applications.

Similar to React Suspense, we can pass the lazily imported module to the , which will only import the module once the module is being requested! While the module is being loaded, we can render a component.

Although loadable components are a great alternative to React Suspense for SSR applications, they're also useful in CSR applications in order to suspend the import of modules.