Frontend Engineering

Production-ready patterns for modern web applications.

Modern Best Practices (January 2026): Next.js 16 + Turbopack, React 19.x + Server Components, TypeScript 5.9+ (strict), Tailwind CSS v4, TanStack Query, Zustand, Vitest (browser mode).

Breaking Changes: Next.js 16 Upgrade Guide

Shared release gates: ../software-clean-code-standard/assets/checklists/frontend-performance-a11y-checklist.md

If you use React Server Components (RSC), treat security advisories as blocking: see data/sources.json (React RSC advisories).

Quick Reference

Workflow

1. Pick a framework using the decision tree.
2. Start from a matching template in assets/.
3. Implement feature-specific patterns from references/.
4. Treat accessibility and performance as release gates (shared checklist above).

Framework Decision Tree

Project needs:
|-- React ecosystem?
|   |-- Full-stack + SEO -> Next.js 16
|   |-- Progressive enhancement -> Remix
|   `-- Client-side SPA -> Vite + React
|
|-- Vue ecosystem?
|   |-- Full-stack -> Nuxt 4
|   `-- SPA -> Vite + Vue 3.5+
|
|-- State management?
|   |-- Server data -> TanStack Query
|   |-- Global client -> Zustand
|   `-- WARNING: DECLINING: Redux
|
`-- Styling?
    |-- Utility-first -> Tailwind CSS v4
    `-- WARNING: DECLINING: CSS-in-JS

Next.js 16 Changes

middleware.ts -> proxy.ts

# Run codemod
npx @next/codemod@canary upgrade latest

# Or manually rename
mv middleware.ts proxy.ts

// After (Next.js 16)
export function proxy(request: Request) {
  // ... logic
}

Cache Components ("use cache")

export default async function Page() {
  "use cache";
  const data = await fetchData();
  return <ProductList data={data} />;
}

React Compiler

// next.config.ts
const nextConfig: NextConfig = {
  experimental: {
    reactCompiler: true,
  },
};

Performance Budgets

Deployment Checklist

Pre-Deployment

• npm run build – no errors
• npm run lint – zero ESLint errors
• vitest run – all tests passing
• Bundle size within budget
• Environment variables set

Accessibility

• axe DevTools – zero critical issues
• Keyboard navigation works
• Color contrast >= 4.5:1
• Screen reader tested

SEO

• Metadata configured
• sitemap.xml generated
• robots.txt configured

Resources

Templates

Related Skills