Ship it

Goal

Understand the build, the CLI entry point, and the checks that guard every change.

From TypeScript to JavaScript

npm run streak:build    # tsc -p streak
node streak/dist/cli.js list

tsc checks the types, then writes plain JavaScript to streak/dist/. Node runs that. The types are gone; the checks already happened.

Key settings in streak/tsconfig.json:

• "module": "nodenext": modern ES modules, the way Node loads them. That is why imports end in .js even in .ts files: they name the file that will exist after the build.
• "verbatimModuleSyntax": true: import type for things that are only types, so they vanish cleanly.
• "target": "ES2023": keep modern JavaScript; Node 22 understands it.

The entry point

run in streak/src/cli.ts does the work and returns text, so it is easy to test. The end of the file connects it to the real world, only when the file is started directly:

const entry = process.argv[1]
if (entry && import.meta.url === pathToFileURL(entry).href) {
  const store = fileStore(process.env.STREAK_FILE ?? 'habits.json')
  const outcome = await run(process.argv.slice(2), store, toDay(new Date()))
  console.log(outcome.output)
  process.exitCode = outcome.code
}

Arguments are read with Node's built-in parseArgs, which is fully typed: values.emoji is string | undefined without any extra work.

Checks on every push

.github/workflows/ci.yml runs, for every change:

npx tsc -p streak --noEmit   # types
npx vitest run               # behaviour
npm run streak:build         # it builds
node streak/dist/cli.js list # and it runs

A red check stops a broken change before anyone else sees it.

Check it works

npm run streak:build
STREAK_FILE=/tmp/streak.json node streak/dist/cli.js add Stretch --weekly 3
STREAK_FILE=/tmp/streak.json node streak/dist/cli.js list

Exercise

You made it. Add a streak remove <id> command, with a test, a Result for "no such habit", and a line in the help text. Then share your fork with the group.