JavaScript Rules

Version: ES2024+, Node.js 24 LTS (recommended)

Tooling

• Linting: ESLint 9 flat config or Biome
• Formatting: Prettier or Biome
• Testing: Vitest (recommended) or Jest
• Runtime: Node.js 24 LTS, Bun 1.x, or Deno 2.x

Best Practices (2026)

• Use ESM modules over CommonJS
• Use async/await (required for modern Node.js)
• Use toWellFormed() for Unicode string handling (ES2024)
• Prefer const over let, avoid var
• Use optional chaining (?.) and nullish coalescing (??)

Framework Selection

• Large-scale apps: NestJS (TypeScript, enforced architecture)
• Lightweight APIs: Express.js or Fastify
• Edge/serverless: Hono (multi-runtime support)

Security (from Node.js best practices)

• Use linter security rules (eslint-plugin-security)
• Limit concurrent requests with rate limiting middleware
• Extract secrets from config files (use environment variables)
• Prevent query injection with ORM/ODM libraries

ES2024 Features

• Object.groupBy() and Map.groupBy() for grouping
• Promise.withResolvers() for promise creation
• Atomics.waitSync() for thread synchronization

MoAI Integration

• Use Skill("moai-lang-javascript") for detailed patterns
• Follow TRUST 5 quality gates