TypeScript Best Practices 2025: Professional Code

The web development stack has fundamentally changed: Performance is a ranking factor – Google evaluates Core Web Vitals as a direct ranking factor. User expectations are rising – Users expect app-like experiences in the browser. Load times over 3 seconds lead to 53% bounce rate. Developer experience counts – Modern tools like TypeScript, Next.js, and Tailwind CSS speed up development. Security is mandatory – Secure coding and DevSecOps must be considered from the start.

From hundreds of projects, we've distilled these best practices: Do: - Use TypeScript from the start - Design mobile-first – over 60% of traffic comes from mobile - Write automated tests – testing isn't a luxury - Consider accessibility from the beginning - Define and maintain a performance budget Don't: - Over-engineering: Not every project needs microservices - Premature optimization: Measure first, then optimize - Vendor lock-in: Build abstraction layers - Accessibility as afterthought: Adding it later is more expensive - Ignore security: A data breach destroys trust permanently