TypeScript Cheat Sheet

TypeScript cheat sheet with real commands and snippets for setup, core workflows, debugging, and production-safe automation patterns. If you are working across tools, pair this with the Angular Cheat Sheet and Bun Cheat Sheet.

Setup and Tooling

Goal: Install and verify language toolchain

# Run npm command
npm install -D typescript @types/node

# Run npx command
npx tsc --init

# Run npx command
npx tsc --version

Core Workflows

Goal: Run and build source code

# Execute npx workflow
npx tsc -p .

# Execute node workflow
node dist/index.js

Goal: Use a practical code snippet

// Generic helper that preserves input type
export function first<T>(items: T[]): T | undefined {
  return items[0];
}

const value = first([1, 2, 3]);

Testing and Formatting

Goal: Run automated tests

# Execute test-related command
npx tsc --noEmit

# Execute test-related command
npm test

Goal: Run lint and formatter checks

# Execute quality command
npx eslint src --ext .ts,.tsx

# Execute quality command
npx prettier -w src

Automation and CI

Goal: Create a repeatable CI shell step

# Run strict shell mode for CI step
set -euo pipefail

# Install dependencies deterministically
npm ci || pip install -r requirements.txt || true

# Run tests and fail fast on errors
npx tsc --noEmit

Debugging and Troubleshooting

Goal: Trace runtime issues

# Print runtime and package manager versions
node --version || python --version || true

# Search stack traces and TODO markers
rg "Traceback|Exception|TODO" .

# Re-run tests with verbose output
npx tsc --noEmit -v || npx tsc --noEmit --verbose || true

Common Gotchas

• Pin TypeScript language/runtime versions in local and CI environments.
• Keep formatting and linting automated to avoid noisy diffs in code review.
• Prefer explicit dependency lock files for reproducible builds.
• Write small, deterministic tests that can run quickly in pre-commit checks.
• Document compiler/interpreter flags used in production builds.

Related Sheets

• Angular Cheat Sheet — daily Angular commands and production-ready examples.
• Bun Cheat Sheet — daily Bun commands and production-ready examples.
• Deno Cheat Sheet — daily Deno commands and production-ready examples.