Besides user interaction, we often have components that aren't visible on the initial page. A good example of this is lazy loading images that aren't directly visible in the viewport, but only get loaded once the user scrolls down.

As we're not requesting all images instantly, we can reduce the initial loading time. We can do the same with components! In order to know whether components are currently in our viewport, we can use the

IntersectionObserver

API, or use libraries such as or to quickly add import on visibility to our application.

Whenever a component is rendered to the screen, detects that the element should be visible on the screen. Only then, it will start importing the module while the user sees a loading component being rendered.

This fallback component lets the user know that our application hasn't frozen: they simply need to wait a short while for the module to be loaded, parsed, compiled, and executed!