You have a solid foundation. Here's a roadmap for what to learn next, in roughly the order we'd suggest. You don't have to follow it exactly, and you definitely don't have to learn it all at once!
Step 1: Build, build, build
The single best thing you can do right now is build more projects. Not tutorials where you follow along, but projects where you decide what to make and figure out how. That's where knowledge turns into skill. Start small. Finish things. A finished small project teaches you more than an abandoned big one.
Step 2: Git and GitHub
Learn version control properly (we gave you a taste in Junior year). Put every project on GitHub. It's your backup, your portfolio, and how teams work together. Almost every developer job expects you to know Git.
Step 3: Level up your HTML and CSS
JavaScript makes pages work, but HTML and CSS make them usable and beautiful. Learn responsive design (making pages work on phones and big screens) with Flexbox and CSS Grid, and learn about accessibility (making your pages usable by everyone, including people who use screen readers or can't use a mouse).
Step 4: Choose your path
From here, JavaScript developers tend to head in one (or more!) directions:
| Path | What you'd build | What to learn next |
|---|---|---|
| Front-end | Websites and web apps that people see and click | A framework (React, Vue or Svelte), TypeScript, a build tool like Vite |
| Back-end | Servers, APIs and databases behind the scenes | Node.js frameworks (like Express or Fastify), SQL databases, authentication |
| Full-stack | Both! | A full-stack framework like Next.js, plus everything above |
| Mobile | Apps for phones | React Native |
| Games | Browser games | Canvas, Phaser, Three.js |
| Desktop | Apps for Windows, Mac and Linux | Electron |
Not sure which to pick? Front-end is a great next step for most people, because you can see your results immediately, and it builds directly on Grades 11 and 12.
Step 5: TypeScript and testing
Once you're comfortable, learn TypeScript (JavaScript with types, from Junior year) and get into the habit of writing tests for your code. Both are used heavily by professional teams.