Hey everyone! I’m a beginner and want to learn how to make Chrome extensions from scratch.

Posted by Responsible-Gene2055@reddit | learnprogramming | View on Reddit | 5 comments

I already know what a Chrome extension and manifest file are, but I want to learn how to actually write the logic using JavaScript and build useful features. My goal is to understand the why and how behind the code, not just copy-paste it.

Can anyone help me with:

A beginner-friendly roadmap for learning extension development step by step?
Good resources or tutorials to start with?
Tips for learning JavaScript specifically for extensions?
Common beginner mistakes to avoid?

If you’ve recently learned this yourself, I’d really appreciate hearing how you approached it too.

Thanks a lot in advance 😊

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Opening-Society7079@reddit

Hi, here is the list:

Web-basics: HTML/CSS fundamentals (tags, selectors, layout)
Core JavaScript syntax & the DOM (querySelector, addEventListener)
GIT! Learn what it is, why, and use it for every project you will ever have.
“Hello World” extension. Follow Chrome’s guide and build the classic toolbar-popup https://developer.chrome.com/docs/extensions/get-started
Manifest V3 essentials
- Understand manifest.json keys (name, action, permissions, background.service_worker).
- Swap the old background page for a service worker and learn its life-cycle quirks (it goes to sleep)
Content scripts & messaging
Inject JS into pages (content_scripts) and pass messages between popup ↔ content ↔ service worker using chrome.runtime.sendMessage and chrome.tabs.sendMessage
Dig into the Chrome APIs
- Tabs, Scripting, Storage (sync/local), Alarms, Commands, i18n.
- Build at least one small feature per API—e.g., a “mute all YouTube tabs” button or a local-storage to-do list.
Packaging & publishing
- Run npm run zip or the Chrome command-line packer.
- Create a store listing, fill in privacy details, and push to Trusted Tester channel first
Tooling & advanced topics
- TypeScript, cross-browser WebExtension polyfills, automated tests, React/Vue

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Opening-Society7079@reddit

Chrome Extension tutorials: https://developer.chrome.com/docs/extensions/get-started#tutorials
Good JS resource: https://javascript.info/

Focus on DOM + browser APIs — Most extension logic is reading/modifying pages or browser state, not heavy algorithms.
Master asynchronous code — Promises, async/await, and event listeners power everything (network calls, storage, alarm triggers).
Use DevTools every day — Inspect pop-ups (Ctrl+Shift+I on the popup), debug service-worker logs in the chrome://extensions page, and set breakpoints in content scripts.

I will recommend beginning with the YouTube beginner's guide into Web by learning HTML, CSS and JS on very basic level just to know how it works. https://www.youtube.com/watch?v=G3e-cpL7ofc (don't be scared of 6 hours, it's a very detailed guide and intro).

Personal advice: if you don't understand something, read it again and again, if you still don't get it => find another explanation. If it doesn't help => more forward, don't worry, you will understand it later. Also, don't try to spend 12h a day in learning, it won't work. If you read any theory, always try to write this code and see if it runs/play with it/try to change. Mechanical memory is very important, if you read without writing any code - you will not understand how it works.

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Responsible-Gene2055@reddit (OP)

wow thank you for your help