JS with Types

Turn on transpile-free type hinting for your vanilla JS projects #JSWithTypes

1. Create a plain JavaScript project

   npm init

2. Turn on type linting 💪

   # Create a properly configured `jsconfig.json`
   npx -p jswt@2.x -- jswt init
   
   # Install @types/node, if needed
   npm install --save '@types/node'

3. Profit!

Works with VS Code out-of-the-box, and Vim + ale.

CommonJS vs ESM

Use v1 for CommonJS, or v2 for ESM.

Watch the Presentation!

https://jswithtypes.com

Layout

Your project will look something like this:

.
├── bin/
├── jsconfig.json
├── node_modules/
│   └── @types/
│       └── node/
├── package-lock.json
├── package.json
├── README.md
├── types.js
└── typings/
    └── overrides/
        └── index.d.ts

Inner Workings

1. Runs tsc --init with these options:

   npx -p typescript@5.x -- \
       tsc --init \
       --allowJs --alwaysStrict --checkJs \
       --module nextnode --moduleResolution nextnode \
       --noEmit --noImplicitAny --target es2024 \
       --typeRoots './typings,./node_modules/@types'

2. Adds the following keys:

   "paths": { "foo": ["./foo.js"], "foo/*": ["./*"] },
   "include": ["*.js", "bin/**/*.js", "lib/**/*.js", "src/**/*.js"]`,
   "exclude": ["node_modules"]

3. Renames tsconfig.json to jsconfig.json \ (and creates some placeholder files and dirs)

Bonus: npm run lint

You may wish to add common script commands for fmt and lint:

npm pkg set scripts.lint="npx -p typescript@5.x -- tsc -p ./jsconfig.json"
npm pkg set scripts.fmt="npx -p prettier@3.x -- prettier -w '**/*.{js,md}'"

Bonus: Vim Config

It should Just Work™, but if your vim setup is a little custom, you may want to add or modify a line like this:

~/.vimrc:

let g:ale_linters = {
\  'javascript': ['tsserver', 'jshint'],
\  'json': ['fixjson']
\}