Posts about js

Running TypeScript in Node without a build step

Node 23 strips types out of the box and TypeScript 5.8 has a flag that keeps your code strippable. For scripts and small services I dropped tsx, though the compiler still has a job.

When I reach for React's memo, useMemo and useCallback

A lot of the memoisation in a React codebase does nothing, and some of it costs more than it saves. These are the few cases where I still use it.

The tsconfig module settings I finally understand

module, moduleResolution and the new verbatimModuleSyntax were three knobs I turned until the errors went away. TypeScript 5.0 finally made me read what they do, and now I know why my Vite app and my Node service need different ones.

TypeScript trusts your API too much, so I added Zod

A backend rename turned a typed field into undefined and the compiler never blinked, because types are gone at runtime. So now the data gets checked where it comes in.

Fixing a laggy search filter with useDeferredValue

Typing into the filter above a long table felt like typing over a bad SSH connection. React 18 has a hook for exactly this and the fix was one line. Well, two.

Why I stopped writing enums in TypeScript

Enums were the first thing I reached for when I started with TypeScript. Then I read what they compile to. A const object does the same job with less magic, and TypeScript 4.9 just added the piece that was missing.

Moving my tests from Jest to Vitest

Eight months ago I left the tests behind when I moved to Vite. Moving them took an evening. Reading them took longer, because most of them tested the wrong thing.

Why React 18 runs your effects twice

We upgraded to React 18 and every request in the dev tools showed up twice. React does that on purpose, as a test, and our effects were failing it.

Moving a Create React App project to Vite

Create React App 5 landed this week after a year of waiting, and I still moved my side project to Vite. It took an evening, mostly spent renaming things.

How to solve missing chunk code splitting errors after deploy

Code splitting is a great way to avoid huge javascript files, but weird things can happen after a deploy. Let's fix that.