The following are practical JavaScript best practices commonly followed by experienced engineers. No dogma — just approaches that save time and reduce bugs.
1) Prefer small, pure functions
Small functions are easier to test and reason about. Aim for functions that do one thing and return predictable outputs.
2) Use TypeScript or tight runtime checks
If you don’t want full TypeScript, add runtime validators for public boundaries (zod, yup). Types catch many mistakes before runtime.
3) Avoid deep mutation
Immutable updates (spread, structuredClone, immer) reduce surprising bugs. If performance demands it, measure and document the trade-off.
4) Handle async errors explicitly
Use try/catch, and fail fast in server code. Prefer returning structured error objects from APIs instead of raw error messages.
5) Test the important things
Unit test business logic, integration test APIs, and add a couple of end-to-end happy path tests for critical flows.
6) Keep dependencies minimal and reviewed
Every dependency is a maintenance cost. Favor small, well-maintained libraries and pin versions in lockfiles.
7) Lint, format, and CI gates
Use ESLint and Prettier, and fail PRs on lint/type errors. CI catches many regressions before they reach main.
8) Log with context
For servers, structured logging (JSON with request IDs) makes debugging production issues much easier.
9) Optimize where it matters
Premature optimization is real — profile before optimizing. Focus on network, DB, and algorithmic hotspots.
10) Write clear, minimal docs
A short README and a few comments for tricky parts go a long way. Documentation is an investment in your future self.
Edge cases & practical tips
- Use feature flags for risky rollouts.
- Keep API contracts small and version them when you need incompatible changes.
- Use a consistent error shape across services to simplify client handling.
Final note
Robust code is less about clever hacks and more about predictable patterns, clear boundaries, and small, deliberate steps. Applying these basics consistently leads to more maintainable and reliable systems.