Next.js is a popular React framework designed for building scalable, production-ready web applications. It provides features like server-side rendering, static site generation, and API routes.
Key features of Next.js include:
While React.js is a library for building UIs, Next.js is a framework built on top of React, providing additional features such as SSR, SSG, and routing out of the box.
Next.js offers:
SSR in Next.js allows pages to be rendered on the server at request time, ensuring that the page's content is available to search engines and improving the initial load time.
SSG generates HTML at build time for fast loading and improved SEO. It’s ideal for pages that don’t change often, such as blogs or marketing pages.
API routes allow you to build backend functionality directly in your Next.js app. These are serverless functions that handle HTTP requests like GET, POST, PUT, etc.
ISR enables static content to be updated after the site has been built, allowing you to regenerate pages in the background while serving static content to users.
Dynamic routes in Next.js are handled using brackets ([]). For example, pages/[id].js will create dynamic routes based on the id parameter.
Next.js automatically splits code by page. This means only the necessary code for each page is loaded, improving performance and reducing bundle size.
The App Router in Next.js is a new routing system introduced to simplify the routing mechanism, offering enhanced flexibility and control compared to the Pages Router.
Layouts in the App Router allow you to structure reusable components across multiple pages, making it easier to manage UI consistency and shared components.
The app directory is used with the new App Router and supports features like layouts, loading states, and more advanced routing capabilities. The pages directory is used in the traditional Pages Router.
Next.js supports SSR and SSG, which generates pre-rendered HTML content, making it more SEO-friendly compared to traditional client-side rendering (CSR).
Environment variables are handled via .env files (e.g., .env.local) and can be accessed in both the client and server-side code using process.env.
Dynamic API routes are created by using the same bracket notation ([param]) in the pages/api directory.
Middleware allows you to run code before a request is completed, enabling features like authentication, logging, or redirecting users.
React Server Components allow parts of the UI to be rendered on the server, reducing the client-side JavaScript bundle size.
React Server Components allow rendering on the server, improving performance by sending only necessary JavaScript to the client.
To use React Server Components in Next.js, create a .server.js file in the appropriate directory, allowing the component to be rendered server-side.
next/link is a React component for client-side navigation, providing prefetching and reducing page reloads, unlike a standard <a> tag.
next/image automatically optimizes images for better performance, including resizing, lazy loading, and WebP support.
Rewrites allow you to map an incoming request path to a different destination without changing the URL in the browser.
next.config.js is a configuration file in Next.js that allows you to customize the build process, routing, environment variables, and more.
Next.js optimizes images by automatically resizing, compressing, and serving them in the most appropriate format for the client.
Hybrid rendering in Next.js allows you to use SSR, SSG, or ISR on a per-page basis, providing flexibility in how content is rendered.
Hybrid rendering offers the ability to combine different rendering strategies to maximize performance, SEO, and flexibility.
Data fetching in Next.js can be done using getStaticProps (SSG), getServerSideProps (SSR), or getInitialProps.
State management in Next.js can be done using React's useState and useContext, or with libraries like Redux, Recoil, or Zustand.
Routing in Next.js is based on the file system. The files in the pages directory automatically become routes.
Nested routing is handled by creating subdirectories inside the pages directory. For example, pages/blog/[id].js supports dynamic routes.
The public folder is used for static assets like images, fonts, or other files that can be accessed directly via URL.
To create a custom 500 error page, create a pages/_error.js file and customize the error handling for both 404 and 500 errors.
File-based routing automatically maps files in the pages directory to routes based on their file names and structure.
You can style components using traditional CSS, CSS-in-JS libraries like styled-components, or CSS modules.
Next.js has built-in support for TypeScript. You can create a tsconfig.json file, and it will automatically detect and work with TypeScript files.
Simply add a tsconfig.json file to your project root. Next.js will automatically configure TypeScript for you, and you can start using .ts and .tsx files.
next/image for imagesISR allows you to update static content after the site is built using revalidate in getStaticProps.
Redirects are configured in next.config.js using the redirects() function.
getStaticProps: Fetches data at build time.getServerSideProps: Fetches data on each request.Store variables in .env.local, and access them with process.env.MY_VAR. Prefix with NEXT_PUBLIC_ to use them in the client.
Use headers() in next.config.js to add custom HTTP headers.
Image component in Next.js?It’s a built-in component that optimizes images with lazy loading, resizing, and format conversion.
Using next/link, prefetching is enabled by default on visible links. You can also manually enable it with prefetch={true}.
useRouter and Link?useRouter: Hook to access routing methods.Link: Component for client-side navigation.Add a middleware.ts file in the root or a route directory to intercept requests and modify behavior.
Runs on the edge (closer to users) for faster response times, used for auth, redirects, rewrites, etc.
Use middleware or HOCs to check authentication before rendering protected routes.
Use libraries like express-rate-limit or custom logic inside API routes to track and limit requests.
revalidate property?It defines how often a page should be regenerated in seconds.
You can deploy to Vercel, Netlify, or any server that supports Node.js. Vercel is the recommended platform.
Install Tailwind, add it to postcss.config.js, and import it in your main CSS file.
next dev, next build, and next start?next dev: Starts the dev servernext build: Builds the app for productionnext start: Starts the production serverIncludes App Router, Server Components, Layouts, React 18 support, and better performance tools.
ISR delivers static pages but allows them to be updated in the background, improving freshness and speed.
Use try-catch blocks, return proper status codes and messages, and log errors.
Use tools like Google Analytics, Plausible, or Vercel Analytics, often via custom _app.tsx.
Create _app.js or _app.tsx inside the pages directory to override default App behavior.
Use _document.js to customize the HTML structure, add fonts, or manage the <html> and <body> tags.
Special files like loading.tsx used to show UI during lazy data fetching or navigation.
Used during ISR or dynamic routes to show a loading state while a page is being generated.
They allow you to load components on demand using next/dynamic.
Define locales and defaultLocale in next.config.js, and Next.js will handle route-based translations.
Allow rendering different layouts or content in parallel within the same page structure.
Enable custom rendering for a nested route from a parent segment without full remounting.
Yes, use next-redux-wrapper to integrate Redux for SSR and SSG support.
Use the Head component from next/head to manage <title>, <meta>, etc.
Use fetch, axios, or getServerSideProps/getStaticProps for server-side fetching.
Create pages/404.js to customize the "Page Not Found" experience.
next export?Exports your Next.js app as a static site with no server rendering or dynamic routes.
Yes, with libraries like Apollo Client or urql.
Use libraries like next-auth, or custom logic with JWTs, cookies, sessions.
Not directly, but you can build PWAs or use APIs with React Native frontends.
Rendering HTML in advance either at build time (SSG) or request time (SSR).
Use packages like next-sitemap or write custom scripts to generate one during build.
Add it to the public folder or generate it dynamically in API routes or middleware.
Use the <link> tag in _document.js or use @next/font for better performance.
Lazy loading in Next.js loads components/images only when they enter the viewport.
Use Jest and React Testing Library for unit/integration tests; Playwright or Cypress for E2E.
Use global state tools like Redux, Context API, Zustand, or Jotai.
Yes. You can use it via API routes or connect in getServerSideProps.
Use useRouter to track path and build a breadcrumb component dynamically.
Use semantic HTML, ARIA labels, and audit with Lighthouse or axe-core.
Use state to conditionally render a loading spinner or use App Router’s loading.tsx.
Use useState, localStorage, or libraries like next-themes.
It’s when content moves during load. Use defined image dimensions, avoid late-loading fonts.
The process where React makes HTML interactive on the client side.
CSR renders in the browser; SSR renders on the server and sends HTML to the browser.
React components rendered on the server to reduce JS sent to the client.
Yes. Read/write cookies in API routes, getServerSideProps, or middleware.
Use client-side fetch to call API routes or use traditional <form> with action set to your route.
Add headers in API routes or middleware.
Use folders like components, pages, lib, styles, public, and hooks for better organization.
Add them to the public folder or use Google Fonts via _document.js.
Use layout components and wrap them in _app.js or App Router’s layout.tsx.
Check user roles in middleware, API routes, or getServerSideProps.
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