Consider rewriting in Typescript

[cypressious]

Since the project is really tiny, it appears to be more work to provide the types separately than just rewrite the whole thing in Typescript.

[foxbenjaminfox]

You're right, it probably would be a good idea to convert it to Typescript. If you'd like to write a PR that does the conversion I'd be happy to merge it, or otherwise I'll find at some point the time to do it myself.