When testing in the console is not enough, and we want to inspect our application while it is running inside the browser, we can use the React Developer Tools.

You can install them as a Chrome extension at the following URL: https://chrome.google.com/webstore/detail/react-developer-tools/fmkadmapgofadopljbjfkapdkoienihi?hl=en.

The installation adds a tab to the Chrome DevTools called React, where you can inspect the rendered tree of components and check which properties they have received and what their state is at a particular point in time.

Props and states can be read, and they can be changed in real time to trigger updates in the UI and see the results straightaway.

This is a must-have tool, and in the most recent versions it has a new feature that can be enabled by ticking the Trace React Updates checkbox.

When this functionality is enabled, we can use our application and visually see which components get updated when we perform a particular action. The updated components are highlighted with colored rectangles, and it becomes easy to spot possible optimizations.