TypeScript catches a large share of bugs while you type, before code ever runs. It adds type checking to JavaScript, so your editor points out errors, refactoring becomes safe, and your code documents itself. Turn on strict mode from the start. The extra time you put into types pays back double in less debugging and confident changes. At NedDev, TypeScript is the standard for every front end.
A missed capital letter in a property name. In JavaScript you discover that only when a user sees a white page and you get an error in production. In TypeScript your editor underlines it red while you are still typing. That one difference, multiplied across thousands of lines of code and months of maintenance, is exactly why we no longer build a front end without TypeScript. It is not a matter of taste, it is risk management.
JavaScript is permissive until it gets painful. You give a function a string where a number was expected, JavaScript shrugs and tries to make something of it, and it only fails somewhere deep in production in a way that is hard to trace. TypeScript checks types while you write. The biggest category of errors we used to see only in tests or with users, the compiler now catches before the code runs even once.
What you concretely gain:
The biggest benefit shows up not when writing new code, but when changing existing code. Rename a function or change a data structure, and TypeScript points out flawlessly every place you have to update. In a large JavaScript codebase such a change is a gamble: you search by name, you hope you found everything, and you discover the missed spot only when something breaks. In TypeScript you know for sure, because the compiler refuses to run until everything checks out.
For platforms that last for years, such as WorldView with its many data layers and complex interactions, this is decisive. Code you touch again in half a year tells you through the types exactly what it expects and returns. The code documents itself, and that documentation never goes out of date, because the compiler enforces that it is correct. A loose README can go stale, a type cannot without your build failing.
Many teams turn on TypeScript but leave strict mode off, and thereby miss at least half the benefit. Without strict mode you can still use any everywhere and ignore null cases, exactly the weak spots TypeScript should protect you against. Strict mode forces you to handle null and undefined cases explicitly, the cases that otherwise cause the crashes. A few settings we turn on by default:
any.Start a new project with strict mode on right away. Migrating to strict afterward is far more painful than doing it right from the start, because then you have to resolve hundreds of existing warnings all at once. The extra strictness sometimes feels difficult and slow at first, but every warning you resolve now is a bug your user never gets to see.
There is another benefit that only becomes visible as a team grows: TypeScript makes implicit knowledge explicit. In a JavaScript codebase, a lot of knowledge about how data should look sits in the heads of the developers who wrote it. That developer leaves, and the knowledge leaves with them. In TypeScript that knowledge is recorded in the types, verifiable by the compiler. A new developer does not have to guess whether a function expects a user object or just an id, because the type says so. That not only speeds up onboarding, it also prevents the whole class of errors that arises when someone makes a wrong assumption about existing code.
The honest side: TypeScript costs a bit more time up front. You write types, you resolve compiler warnings, and with an external library you sometimes have to search for the right type definitions. But that investment pays back amply over the lifespan of a project. Less debugging, faster code reviews because the intent of the code is clear, and new team members who onboard faster because the types tell them how everything fits together without anyone having to explain it.
We build every front end with TypeScript on Next.js 16 and React 19, strict mode on from the first line. For a team that works with the same codebase for years, it is not a luxury but the foundation of maintainable software. See how we apply this in projects like WorldView. Want to set up your front end to be future-proof or migrate an existing codebase? Take a look at our front-end development service.
Up front it costs a bit more time to write types, but that investment pays back amply. You have less debugging because bugs are caught while typing, refactoring becomes safe, and code reviews go faster because the intent is clear. Over the lifespan of a project, TypeScript saves a lot of time on balance.
Strict mode is a set of stricter settings that forces you to handle null and undefined cases explicitly, exactly the cases that cause crashes. Yes, turn it on, preferably from the start of a project. Migrating to strict mode afterward is far more painful than doing it right immediately.
Yes. TypeScript can be introduced step by step alongside JavaScript, file by file. You can set strict mode more loosely at first and gradually tighten it. For large existing codebases this is the practical route, although a new project that starts fully strict right away delivers the most benefits.