Next.js: The Definitive Guide to the Most Popular React Framework

Next.js has become the most popular React framework for building modern web applications. With its focus on server-side rendering (SSR), static generation, and an excellent development experience, Next.js offers everything you need to build high-performance, scalable web applications.

Why Next.js?

Main Features

1. Hybrid Rendering

   • Server-Side Rendering (SSR)
   • Static Site Generation (SSG)
   • Client-Side Rendering (CSR)
   • Incremental Static Regeneration (ISR)

2. Automatic Optimizations

   • Image Optimization
   • Font optimization
   • Script optimization
   • Zero config

3. Developer Experience

   • Fast Refresh
   • TypeScript Support
   • File-system routing
   • API Routes

First Steps

Creating a Project

npx create-next-app@latest mi-proyecto
cd mi-proyecto
npm run dev

Project Structure

├── app/
│   ├── layout.tsx
│   ├── page.tsx
│   └── globals.css
├── public/
│   └── images/
├── components/
│   └── ui/
├── lib/
├── next.config.js
└── package.json

Routing in Next.js 14

Basic Pages

// app/page.tsx
export default function Home() {
  return (
    <main>
      <h1>Bienvenidos a Next.js</h1>
    </main>
  );
}

Dynamic Routes

// app/blog/[slug]/page.tsx
export default function BlogPost({ params }: { params: { slug: string } }) {
  return (
    <article>
      <h1>Post: {params.slug}</h1>
    </article>
  );
}

Shared Layout

// app/layout.tsx
import { Inter } from 'next/font/google';
const inter = Inter({ subsets: ['latin'] });

export default function RootLayout({
  children,
}: {
  children: React.ReactNode;
}) {
  return (
    
      
        <nav>
          {/* Navegación común */}
        </nav>
        {children}
      
    
  );
}

Data Fetching

Server Components

// app/posts/page.tsx
async function getPosts() {
  const res = await fetch('https://api.ejemplo.com/posts', {
    next: { revalidate: 3600 } // Revalidar cada hora
  });
  return res.json();
}

export default async function Posts() {
  const posts = await getPosts();

  return (
    <div>
      {posts.map(post => (
        <article key="{post.id}">
          <h2>{post.title}</h2>
          <p>{post.excerpt}</p>
        </article>
      ))}
    </div>
  );
}

Static Generation

// app/posts/[id]/page.tsx
export async function generateStaticParams() {
  const posts = await getPosts();

  return posts.map((post) => ({
    id: post.id.toString(),
  }));
}

export default async function Post({ params }: { params: { id: string } }) {
  const post = await getPost(params.id);

  return (
    <article>
      <h1>{post.title}</h1>
      <div>{post.content}</div>
    </article>
  );
}

API Routes

// app/api/posts/route.ts
import { NextResponse } from 'next/server';

export async function GET() {
  try {
    const posts = await getPosts();
    return NextResponse.json(posts);
  } catch (error) {
    return NextResponse.json(
      { error: 'Error al obtener posts' },
      { status: 500 }
    );
  }
}

export async function POST(request: Request) {
  try {
    const data = await request.json();
    const newPost = await createPost(data);
    return NextResponse.json(newPost, { status: 201 });
  } catch (error) {
    return NextResponse.json(
      { error: 'Error al crear post' },
      { status: 500 }
    );
  }
}

Optimizations

Images

import Image from 'next/image';

export default function Profile() {
  return (
    <image src="/perfil.jpg" alt="Foto de perfil" width="{500}" height="{300}" priority></image>
  );
}

Fonts

import { Roboto } from 'next/font/google';

const roboto = Roboto({
  weight: ['400', '700'],
  subsets: ['latin'],
  display: 'swap',
});

export default function Layout({ children }) {
  return (
    <div classname="{roboto.className}">
      {children}
    </div>
  );
}

State Management

Client Components

'use client';

import { useState } from 'react';

export default function Counter() {
  const [count, setCount] = useState(0);

  return (
    <div>
      <p>Contador: {count}</p>
      <button onclick="{()"> setCount(count + 1)}>
        Incrementar
      </button>
    </div>
  );
}

Stylization

CSS Modules

// components/Button.tsx
import styles from './Button.module.css';

export default function Button({ children }) {
  return (
    <button classname="{styles.button}">
      {children}
    </button>
  );
}

Tailwind CSS

export default function Card({ title, content }) {
  return (
    <div classname="p-6 max-w-sm mx-auto bg-white rounded-xl shadow-lg flex items-center space-x-4">
      <div>
        <div classname="text-xl font-medium text-black">{title}</div>
        <p classname="text-gray-500">{content}</p>
      </div>
    </div>
  );
}

Middleware

// middleware.ts
import { NextResponse } from 'next/server';
import type { NextRequest } from 'next/server';

export function middleware(request: NextRequest) {
  // Verificar autenticación
  const token = request.cookies.get('token');

  if (!token) {
    return NextResponse.redirect(new URL('/login', request.url));
  }

  return NextResponse.next();
}

export const config = {
  matcher: '/dashboard/:path*',
};

Testing

// __tests__/Home.test.tsx
import { render, screen } from '@testing-library/react';
import Home from '@/app/page';

describe('Home', () => {
  it('renders a heading', () => {
    render(<home></home>);
    const heading = screen.getByRole('heading', { level: 1 });
    expect(heading).toBeInTheDocument();
  });
});

Deployment

Production Configuration

// next.config.js
/** @type {import('next').NextConfig} */
const nextConfig = {
  images: {
    domains: ['tu-dominio.com'],
  },
  async redirects() {
    return [
      {
        source: '/old-page',
        destination: '/new-page',
        permanent: true,
      },
    ];
  },
};

module.exports = nextConfig;

Best Practices

1. Code Organization

   app/
   ├── (auth)/
   │   ├── login/
   │   └── register/
   ├── (dashboard)/
   │   ├── profile/
   │   └── settings/
   └── (marketing)/
       ├── about/
       └── contact/

1. Handling Error

   // app/error.tsx
   'use client';

   export default function Error({
     error,
     reset,
   }: {
     error: Error & { digest?: string };
     reset: () => void;
   }) {
     return (
       <div>
         <h2>¡Algo salió mal!</h2>
         <button onclick="{()"> reset()}>Intentar de nuevo</button>
       </div>
     );
   }

1. Loading States

   // app/loading.tsx
   export default function Loading() {
     return (
       <div classname="flex items-center justify-center">
         <div classname="animate-spin rounded-full h-32 w-32 border-b-2 border-gray-900"></div>
       </div>
     );
   }

Conclusion

Next.js 14 offers:

• Exceptional performance
• Excellent DX (Developer Experience)
• Scalability
• Rendering flexibility
• Seamless integration with React

It is the ideal choice for:

• Business web applications
• E-commerce sites
• SaaS Applications
• Dynamic content sites

Additional Resources

• Official Documentation
• Next.js Examples
• Learn Next.js
• Vercel Blog

Are you using Next.js in your projects? What features do you find most useful? Share your experience in the comments! ?

nextjs #react #webdev #javascript

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