Because TypeScript is great! It has all of the benefits of JavaScript, with the addition of a flexible and robust type system far beyond the basic 7-8 types that exist in vanilla JS. Aside from the obvious safety benefits of strong typing, it also empowers your editor/IDE with an understanding of the types that are used in your code, meaning awesome workflow emprovements like better linting, instant type-checking, and even type-sensitive autocomplete! If you haven't tried TypeScript yet, give it a shot... it really is worth it!

Essentially, a custom package transpiler serves as a shim between Atom and your package, allowing Atom to require() files written in languages that it doesn't natively understand. In this case, it takes responsibility for your package's TypeScript files, and converts them to JavaScript on-demand. Atom then caches the transpiled code for each file, only asking for re-transpilation if the cache becomes invalid (such as when the package is updated.) If Atom already has your entire package cached, the TypeScript compiler is never even loaded, and performance-wise, it functions just as if you had written the entire package in JavaScript to begin with!

The first time a user activates your package after installing it, there may be a brief delay (sometimes about a second) as Atom converts the downloaded TypeScript source files to JavaScript. On subsequent activations, however, Atom will use the cached build output generated on the previous activation, meaning that the long-term increase in activation time is near-zero (well under 10ms even for reasonably large packages.) This small difference is mainly due to Atom confirming that the cached version of each file it requires is still valid; other than that, there is no long-term performance penalty at all vs. native JavaScript packages.

Yes, absolutely. In fact, this package is written in TypeScript and transpiled prior to publishing. However, it's a bit more complicated for Atom packages than for NPM packages, since Atom packages are hosted directly from their GitHub repo, rather than uploaded to an external package repository like npm. Users download your package exactly as it exists on your master branch, so if you want your code to be transpiled prior to distribution, you'll have to actually commit the transpiled output to the repo (e.g. by setting up a pre-commit hook to run tsc,) and the user will end up downloading both the TypeScript and JavaScript versions, anyway. With a custom transpiler, all that mess can be avoided. The transpilation of your TypeScript code is handled automatically by Atom itself, with zero performance penalty after the first time the package is installed and run.

Right now, the best way to help out with atom-ts-transpiler is simply to use it and provide feedback if you feel there are any improvements that can be made. Long-term stability is one of our foremost goals, and we feel like we've achieved it; the project has 100% unit test coverage, and integration tests that are run against each new release of Atom, so there's no need to worry about your package suddenly breaking because of an update. Take it for a spin and let us know what you think! 🙂

If you'd like to contribute in a more direct way, see our Contribution Guide and Code of Conduct on GitHub. We always welcome issues and pull requests from the community, if you find a bug or if you think there are improvements to be made.