WIP: initial content for article

apps/site/pages/en/learn/typescript/publishing.md

@@ -5,3 +5,179 @@ authors: JakobJingleheimer
 ---
 
 # Publishing a TypeScript package
+
+This article augments TypeScript's [Publishing guide](https://www.typescriptlang.org/docs/handbook/declaration-files/publishing.html) with specifics for native node support.
+
+Some important things to note:
+
+- Node runs typescript via a process called "type stripping", wherein node (via SWC under the hood of [Amaro](https://github.com/nodejs/amaro)) removes TypeScript-specific syntax, leaving behind vanilla JavaScript (which node already understands). This behaviour is enabled by default of node version 23.6.0.
+
+  - Node does **not** strip types in `node_modules`. This decision was at the request of TypeScript maintainers because it can cause significant performance issues for the official compiler (`tsc`).
+
+- TypeScript-specific features like `enum` still require a flag ([`--experimental-transform-types`](https://nodejs.org/api/typescript.html#typescript-features))
+
+## What to do with your types
+
+### Treat them like a test
+
+The purpose of types are to warn an implementation will not work:
+
+```ts
+const foo = 'a';
+const bar: number = 1 + foo;
+//    ^^^ Type 'string' is not assignable to type 'number'.
+```
+
+TypeScript has warned you that the above code will not behave as intended, just like a unit test warns you code does not behave as intended.
+
+Your IDE (ex VS Code) likely has built-in support for TypeScript, displaying errors as you work. If not, and/or you missed those, CI will have your back.
+
+```yaml displayName=".github/workflows/ci.yml"
+name: Tests
+
+on:
+  push:
+    branches: ['main']
+  pull_request:
+    branches: ['main']
+
+jobs:
+  lint-and-check-types:
+    # Separate these from tests because
+    # they are platform and node-version independent.
+
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version-file: '.nvmrc'
+          cache: 'npm'
+      - name: npm clean install
+        run: npm ci
+      - run: node --run lint
+      - run: node --run types:check
+
+  test:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        node:
+          - version: 23.x
+          - version: 22.x
+          # glob is not backported below 22.x
+      fail-fast: false # prevent a failure in one version cancelling other runs
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Use Node.js ${{ matrix.node.version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node.version }}
+          cache: 'npm'
+      - name: npm clean install
+        run: npm ci
+      - run: node --run test
+```
+
+```json displayName="package.json"
+{
+  "version": "0.0.0",
+  "name": "example-ts-pkg",
+  "scripts": {
+    "lint": "…",
+    "types:check": "tsc --noEmit"
+  },
+  "optionalDependencies": {
+    // This is used only in CI.
+    // Marking it 'optional' avoids installing on your local
+    // (where you probably won't use it).
+    "typescript": "^5.7.2"
+  }
+}
+```
+
+```json displayName="tsconfig.json"
+{
+  "compilerOptions": {
+    "declarationMap": true,
+    "declaration": true,
+    "emitDeclarationOnly": true,
+    "esModuleInterop": true, // Flux Capacitor: The universe breaks without it, but nobody knows what it does.
+    "module": "NodeNext",
+    "moduleResolution": "NodeNext",
+    "target": "ESNext"
+  },
+  // These may be different for your repo:
+  "include": "./src",
+  "exclude": ["**/*/*.test.*"]
+}
+```
+
+### Generating type declarations
+
+Type declarations (`.d.ts` and friends) provide type information as a sidecar file, allowing the execution code to be vanilla JavaScript whilst still having types.
+
+Since these are generated based on source code, they can be built as part of your publication process and do not need to be checked into your repository.
+
+Take the following example (a [GitHub Action](https://github.com/features/actions)), where the type declarations are generated just before publishing to the NPM registry.
+
+```yaml displayName=".github/workflows/publish.yml"
+name: Publish to NPM
+on:
+  push:
+    tags:
+      - '**@*'
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+
+    permissions:
+      contents: read
+      id-token: write
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version-file: '.nvmrc'
+          registry-url: 'https://registry.npmjs.org'
+      - run: npm ci
+
+      # You can probably ignore the boilerplate config above
+
+      - name: Generate types
+        run: node --run types:generate
+
+      - name: Publish with provenance
+        env:
+          NODE_AUTH_TOKEN: ${{ secrets.NPM_TOKEN }}
+        run: npm publish --access public --provenance
+```
+
+```diff displayName="package.json"
+{
+  "name": "example-ts-pkg",
+  "scripts": {
+    "types:check": "tsc --noEmit",
++   "types:generate": "tsc"
+  }
+}
+```
+
+```text displayName=".npmignore"
+*.test.*
+*.fixture.*
+fixture.*
+fixtures
+```
+
+#### Breaking this down
+
+Generating type declarations is deterministic: you'll get the same output from the same input, every time. So there is no need to commit these to git.
+
+[`npm publish`](https://docs.npmjs.com/cli/v11/commands/npm-publish) grabs everything applicable and available at the moment the command is run; so generating type declarations immediately before means those are available and will get picked up.
+
+By default, `npm publish` grabs (almost) everything (see [Files included in package](https://docs.npmjs.com/cli/v11/commands/npm-publish#files-included-in-package)). In order to keep your published package minimal (see the "Heaviest Objects in the Universe" meme about `node_modules`), you want to exclude certain files (like tests and test fixtures) from from packaging.