Mastering Chrome DevTools for Frontend Development and Debugging

If you’re building anything on the web and not using your browser’s developer tools, then you might as well be running blindly. I think this way because the dev tools are there to help with developers’ experience, and make it so easy to find a bug and nip it from its root source.

In this article I’d be speaking mainly to the Chrome DevTools as it’s my favorite and go to anytime anyday! I love the Chrome DevTools because it has a lot of potential, and as you may also have observed, gets new features so much frequently than a lot of, if not all, other browsers.

Over time, with more than half a decade spent on building responsive and intuitive web applications, I’ve come to rely a lot on Chrome DevTools not just to inspect elements or observe warnings and errors in the console, but to really debug logical flows, styles and performance of my apps. Whether it’s an element that just refuses to center or a page that overflows or behaves weirdly during scroll, DevTools has the answers you need if you know where to look.

I will do my best to break down how I use Chrome DevTools to debug my projects from a real-world developer’s lens.

Debugging Styles?: The Element Panel is Your Best Friend

Let’s say I’m working on a page and the layout breaks, or something just seems off. The “Elements” panel is my first stop.

1. Inspect the DOM

• Right-click any part of the UI and then click on Inspect.

• Make sure you’re in the Elements tab in the developer tools section.

• You should see a live view of the DOM with the ability to expand and collapse nodes, like your JSX or HTML, depending on what you’re building with.

2. Style Live-Editing

• Just below or on the right of the Elements tab (depending on how your dev tools is aligned), under the "Styles" tab, you can:

  • View applied CSS, inherited rules, and overridden styles (crossed out).

  • Directly edit styles, toggle declarations, or add new rules and see their effects play out in real time.

• Hover over any property in the DevTools, and you’d see visual guides like padding, margins, etc., in real-time on the page.

3. Box Model Visualizer

• Scroll to the bottom of the Styles tab, and you’d see the Box Model. It gives you access to a visual breakdown of the margin, border, padding, and content dimensions.

• Also, hovering over each part of the box model shows you visual guides on the page in real time.

• this helps me quickly spot issues with spacing or overflow.

4. Computed Styles

• Most of the time, styles are deeply nested or dynamically applied, hence “computed”.

• This "Computed" tab shows the final rendered value for every CSS property and is great for confirming what’s actually being used in rendering the components.

Debugging Performance?: The Lighthouse and Performance Tabs

Now, if your app feels sluggish or slow, it’s time to switch gears and speed things up!

1. Run a Lighthouse Report

Start with an audit:

• Open the DevTools and go to the “Lighthouse” tab.

• Generate a report for performance, accessibility, best practices, and SEO categories by clicking on the “Analyze page load” button.

• It would give you a quick snapshot of the following metrics:

  • First Contentful Paint (FCP)

  • Largest Contentful Paint (LCP)

  • Total Blocking Time (TBT)

  • Cumulative Layout Shift (CLS)

  • Speed Index (SI)

• Also, you’d get insights on how to optimize for these:

  • Time to Interactivity

  • Javascripts minification

  • Unused JavaScript or CSS

  • Image optimization tips

  • Third party usage

This isn’t just about scores. I use it to find low-hanging fruits that I can touch up easily to help speed up my UI and give better experiences to my users.

2. Record a Performance Trace

   

For more indepth debugging, you’d need to:

• Click on the “Performance” tab.

• Then, click Record, interact with your page, and then stop recording.

  

  

• You’ll get a frame-by-frame timeline of the following:

  • Scripting, rendering, painting activities

  • Long tasks (usually caused by expensive JS execution)

  • FPS (frames per second) and dropped frames

This helps me track down why a button takes 2 seconds to respond or why animations feel broken.

You can also control the Environment settings such as the CPU and network speed just to test for those scenarios.

3. Layout Shift Debugging

Want to check if things jump around while loading?

• The Performance tab highlights Cumulative Layout Shifts (CLS).

• You’ll literally see when and where a layout reflow happened.

Other Tools I Also Use Frequently

• Network tab: Here, you can check what’s loading, what’s slow, what’s failing, etc. You can filter the network requests by a couple of flags like Fetch/XHR requests, CSS, JS, Font, etc. I also throttle the network speed so as to test how my app performs on slower network speeds.

  Another thing I also do is to enable the “Preserve log” checkbox. This helps me refresh the page without having to worry about losing any of the logs from previous loads.
  Then, sometimes, I disable cache just to be sure I’m getting fresh requests loaded.

  

• Application tab: I use this to view the localStorage, sessionStorage, cookies, IndexedDB, shared and cached storages, Essentially, you can view everything storage here, lol, which is so helpful for debugging auth and caching. Service workers and background services are also accessible here.

  

• Rendering tab: You can access a list of stats and emulations here, by clicking on the 3 dots at the top right and then “Run command”. You can enable Paint flashing, Layout shift regions, FPS meter for live visual insights, etc.

  

• Console tab: This tab is definitely one of every developer’s favorite, lol. You get to log anything to the browser console (console.log) and see the logs here. This helps a lot with verifying what is and what is not.

  

• AI assistance tab: You get to ask questions here, as much as you’d like. Although it’s still experimental, this tab can be very useful.

  

  You can select any item at all in either of the listed tabs and ask AI about them. For instance, you can do this in the network tab;

  

In Conclusion

The DevTools is more than an inspector, it’s an amazing tool for debugging your web apps. And now, with AI, the DevTools has got even more resourceful with AI insights and “Ask AI” features. Once you get comfortable using it intentionally, you’ll start solving UI issues faster, with more confidence, and fewer logs to the console. 😉

If you’re just getting started, don’t feel overwhelmed. Start by inspecting and editing styles live. Then build up to using the Performance tab and Lighthouse. It’s one of those skills that compound over time.

And remember, the best way to learn how to use the DevTools is to break stuff and fix it using the DevTools. 😄

Up next, I will be writing about how to use some other browser extensions like the React Developer Tools, Redux DevTools, etc to supercharge your browser DevTools. These would give you access to other features that’d help you inspect and profile the behaviour of your components and redux states.

See you in the next one! 💪