TypeScript Basics for JavaScript Developers

I'd been writing JavaScript for years. It worked fine. Sure, I'd catch bugs at runtime that could have been caught earlier, but that's just how it was, right?

Then I joined a team that used TypeScript, and I had to learn it. I wasn't excited. More syntax to learn, more things to configure. But after a few weeks, I started seeing the benefits.

The errors were annoying at first. I'd write perfectly valid JavaScript, and TypeScript would complain. "This could be undefined." "This type doesn't match." I spent more time fixing type errors than writing features. But here's the thing—those errors were catching real bugs. Bugs that would have shown up in production. Bugs that would have taken hours to debug. TypeScript was forcing me to think about edge cases I'd been ignoring.

Interfaces were the first feature that clicked. Instead of hoping an object had the right properties, I could define exactly what it should look like. Then TypeScript would check it for me. Type inference was another win. I didn't have to type everything explicitly. TypeScript figured out most types on its own. I only needed to add types where they helped.

I started by adding types to new code only. Existing JavaScript stayed as-is. Then I'd gradually add types to files I was already working on. No big rewrite, just incremental improvement. The type system felt restrictive at first, but I learned to work with it instead of against it. Instead of using any everywhere, I'd figure out the right type. It made me think more carefully about my code structure.

I still write JavaScript for small scripts and quick prototypes. But for anything substantial, TypeScript is worth it. The initial learning curve pays off in fewer bugs and better IDE support. The key is not to fight it. Let TypeScript help you. Start with basic types, learn more advanced features as you need them. You don't have to master everything at once.

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