# Skill: JavaScript/TypeScript
**Trigger:** javascript, typescript, node, npm, js code
**Description:** JavaScript/TypeScript development — npm, testing, linting, best practices.
## Body
1. Init: npm init or pnpm init
2. TypeScript: npx tsc --init, use strict mode
3. Dependencies: npm install <pkg>, check package.json
4. Format: npx prettier --write .
5. Lint: npx eslint . --fix
6. Test: npx jest or npx vitest
7. Use const/let, avoid var
8. Use async/await, avoid callback hell
9. Use optional chaining (?.) and nullish coalescing (??)
10. TypeScript: prefer interfaces for objects, strict null checks