Just as developers can run
meteor create --react my-react-app
meteor create --minimal my-minimal-app
meteor create --bare my-bare-app
meteor create --full my-full-app
they can now run
meteor create --typescript my-typescript-app
to produce a new TypeScript application, based on the --react application,
configured using a recommended tsconfig.json file.
This app represents the current best/simplest-known way to set up a
Meteor-compatible TypeScript application, but it is still very much a work
in progress. Please feel free to submit pull requests to improve it, or
create issues to discuss how it should work.
For example, the community-maintained @types/meteor package covers all the
core packages used by this starter application, but it has not been
updated in a while, so there will no doubt be meteor/* packages with
missing types. In future versions, Meteor should ideally generate the
appropriate .d.ts files from TypeScript package source code, so that no
separate @types/meteor/* declarations need to be maintained.
These changes pave the way for incrementally converting the implementation
of Meteor's command-line tool to TypeScript, which should have profound
benefits for self-documentation via types, as well as substantially
improving navigability and approachability for community contributors.
Just imagine being able to auto-complete the fields of the various
File-like classes currently floating around the codebase, instead of
having to track down their implementations every time. TypeScript was
designed with large projects like Meteor in mind, and it seems
increasingly irresponsible to forgo the benefits of a type system by
relying on the expertise of a few core contributors who know the codebase
inside and out. I am one of those few people, and I am very excited to
have the assistance of a type system, so I can only imagine how
transformative and empowering it will be for everyone else.
If you've ever wanted to get involved in core Meteor development, picking
a few meteor/tools modules to convert to TypeScript is a great way to get
to know that part of the codebase, while also making things easier for
everyone else who interacts with that code in the future.
Because we already compile meteor/tools using Babel, it makes the most
sense to use Babel's @babel/preset-typescript to compile .ts files:
https://babeljs.io/docs/en/next/babel-preset-typescript.html
Using Babel also means we get to keep all of our current advanced
compilation strategies, such as using Reify to compile module syntax:
https://www.npmjs.com/package/reify
Since we're using Babel, the meteor/tools/tsconfig.json file exists mostly
for the benefit of external tools like VSCode, rather than as a source of
truth for compilation behavior.
Despite our existing convention of including explicit .js file extensions
when importing modules, TypeScript and VSCode strongly encourage omitting
the file extension, so the import can be resolved to a .ts file in
development or a .js file when compiled. Although I find this ambiguity
somewhat unfortunate, it makes sense to follow community norms, at least
until Node.js begins supporting .ts modules by default.
