I've been working on a little side project and I just wanted to share it with you so that maybe you can find some use for it in your own projects.

typed is similar to superstruct and zod in that it validates data at runtime and it is type-safe but what's different about it is that it comes in a tiny package (1kb) with an ESM build and it also outperforms them by a significant amount.

Here is where my original post would have ended, but somebody mention in the comments that I should tease you with some examples (yes, my marketing skills suck!).

So before I show some examples let me explain why I made it in the first place. The first reason was curiosity: build it to understand how other libraries work. typed actually borrows some type definitions from superstruct because when I started writing this library I had more limited knowledge about more advanced TypeScript topics.

The second reason was that I needed to complement a library I made for writing type-safe JSON APIs. It started as a nicer way to write next.js handlers and I'll soon migrate to the server (yes, I know all cool kids are writing Serverless code this days but I still enjoy coding good old node servers) but I needed a library to validate incoming JSON and in case of failure, reply with a 400 Bad Request error.

The third reason is that I stopped using GraphQL on my personal projects and I switched back to plain fetch requests using Vercel's SWR (stale while revalidate). The thing is that I was missing all the type-safe features that apollo and codegen was giving me.

To demonstrate the second reason, let me show you how I'd like to write a restful endpoint:

import * as T from 'typed'

enum PostStatus {
  draft,
  published,
}

const inputType = T.object({
  title: T.string,
  body: T.string,
  tags: T.array(T.string),
  status: T.enums(PostStatus),
  publishedAt: T.optional(T.asDate),
})

// The request handler
export const createPost = post(async (request) => {
  const data = await request.json(inputType);
  const post = await prisma.post.create({ data });
  return Response.json(post, HttpStatus.CREATED)
})

To demonstrate the third reason, here's is a practical example that you can explore on codesandbox.

Anyways, I hope you find it useful as I do on my own projects. Feel free to reach out if you have any questions.