typescript-ci-setup

TypeScript CI Setup

Multi-step workflow to create a production-grade TypeScript CI pipeline.

When to Use

• New TypeScript project needs CI from scratch
• Existing project has incomplete or fragile CI
• Adding type-check gates, security scanning, or lockfile enforcement

Pipeline Layers (in order)

Each layer gates the next. If a layer fails, the pipeline stops.

1. Install — Lockfile-based (npm ci / pnpm install --frozen-lockfile)
2. Type check — tsc --noEmit (independent of bundler)
3. Lint — ESLint with typescript-eslint type-checked rules
4. Format check — Prettier or Biome (--check mode)
5. Test — Vitest/Jest with coverage threshold
6. Build — Production build (Vite, tsup, esbuild, webpack)
7. Audit — npm audit --audit-level=high or equivalent
8. Code scanning (optional) — CodeQL for JavaScript/TypeScript

Steps

1. Choose Package Manager & Lockfile Strategy

Manager	CI Install Command
npm	npm ci
pnpm	pnpm install --frozen-lockfile
yarn	yarn install --immutable
bun	bun install --frozen-lockfile

The lockfile must be committed. CI must fail if the lockfile is out of sync.

2. Create Workflow File

For GitHub Actions: .github/workflows/ci.yml

name: CI
on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

jobs:
  ci:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version-file: .node-version
          cache: npm

      - run: npm ci
      - run: npx tsc --noEmit
      - run: npx eslint .
      - run: npx prettier . --check
      - run: npx vitest run --coverage
      - run: npm run build
      - run: npm audit --audit-level=high

3. Configure tsconfig for Strictness

Minimum recommended flags:

{
  "compilerOptions": {
    "strict": true,
    "noUncheckedIndexedAccess": true,
    "exactOptionalPropertyTypes": true,
    "useUnknownInCatchVariables": true,
    "noImplicitOverride": true,
    "noPropertyAccessFromIndexSignature": true,
    "isolatedModules": true,
    "verbatimModuleSyntax": true,
    "skipLibCheck": false
  }
}