Next.js

Next.js is a JavaScript open-source framework built on React to create full-stack web applications. Next.js was developed by Guillermo Rauch and introduced by Vercel in 2016. Over time, Next.js has emerged as the most popular framework in React, being used by numerous websites like Netflix, Uber, TikTok, Twitch, Nike, and Starbucks.

While the conventional React application renders everything on the client side (CSR), Next.js offers various rendering mechanisms at the developer's disposal, namely Server-Side Rendering (SSR) , Static Site Generation (SSG) , Incremental Static Regeneration (ISR) , and Client-Side Rendering (CSR).

The second routing system in Next.js is the App Router, which was added starting from version 13+. It relies on the concept of React Server Components and allows server-side component fetching to create efficient initial page loads by minimizing the amount of client-side JavaScript.

A crucial advantage of using Next.js is the full-stack nature of its functionality. With the help of Route Handlers (route.ts files within the app/ folder), it becomes possible to define API routes that can process any kind of request (GET, POST, PUT, PATCH, DELETE). The routes may parse request body, query parameters, headers, and cookies and send back any kind of response (JSON, XML, plain text, or streaming).

There is also Middleware, which is executed before the requests are processed and enables authentication, A/B testing redirection, modification of request/response headers, and URL rewriting.

The framework is ready for production with features such as image optimization (next/image), font optimization, fast refresh, TypeScript support, environment variables, and automatic code splitting. The deployment process is straightforward using Vercel (the parent company of Next.js); however, Next.js can be deployed anywhere with Node.js support.

Key Features

App Router (React Server Components): A contemporary routing system featuring nested, parallel, and intercepting routes. Data is fetched by components server-side, hence no JavaScript on the client.

Route Handlers (API Routes): API endpoint creation with route.ts files inside app/. Allows use of GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS. Any content type can be returned.

Middleware: A single middleware.ts file that executes before the requests. Useful for authentication, redirects, rewrites, A/B tests, and headers.

Various Rendering Methods: SSR (server rendering per request), SSG (static site generation at build time), ISR (static generation with background updates), and CSR (client-only rendering).

Routing Using Files: Route configuration based on folder layout. Dynamic routing with help of [param]. Layouts stay active between pages.

Data Retrieval: Server Components retrieve data directly. Client Components retrieve data using fetch with cache control. Route Handlers include API level handling.

Built-in Optimizations: Image optimizations, next/image, automatic font optimizations, script optimizations, and static asset delivery.

TypeScript Compatibility: Complete TypeScript compatibility with automatic type inference for routes and context.

Environment Variables: Inbuilt support for .env.local, .env.development, and .env.production files, exposing environment variables prefixed by NEXT_PUBLIC_ to browser.

Middleware Configuration: Use config.matcher to configure which routes middleware should run on, reducing unnecessary processing.

Caching Control: Route Handlers can enable static caching by using export const dynamic = 'force-static' for GET routes.

Error Handling: exception handling through try/catch blocks in Route Handler; custom HTTP status codes (200, 201, 204, 400, 401, 403, 404, 500, etc.).

Request/Response Utilities: classes NextRequest and NextResponse augment web API by including useful functions such as redirect(), rewrite(), json(), and cookie utilities.

Static Export (Single Page Application mode): output: ‘export’ option in config exports code as static HTML/CSS/JS. Static GET