Server-side rendering (SSR) is a technique used to improve the performance of web applications by rendering the initial HTML on the server, rather than on the client. This can improve the time-to-first-paint (TTFP) and the perceived performance of your application.
Next.js is a popular framework for building React applications that supports server-side rendering out of the box. In this article, we'll explore how to use Next.js with React to implement server-side rendering.
What is Next.js?
Next.js is a framework for building React applications that provides a number of features out of the box, including:
- Server-side rendering
- Automatic code splitting
- Static file serving
- API routes
These features make it easier to build high-performance React applications that are optimized for both the server and the client.
Getting Started
To get started with Next.js, you'll need to have Node.js installed on your machine. You can download the latest version of Node.js from the official website.
Once you have Node.js installed, you can create a new Next.js project using the following command:
npx create-next-app my-app
This will create a new Next.js project in a directory called my-app. You can navigate to this directory and start the development server using the following command:
cd my-app
npm run dev
This will start the development server and open your application in a new browser window at http://localhost:3000.
Creating a New Page
In Next.js, each file in the pages directory is treated as a separate page. To create a new page, simply create a new file in the pages directory with the name of the page. For example, to create a new page called about, create a file called about.js in the pages directory with the following contents:
import React from 'react';
function About() {
return (
<div>
<h1>About</h1>
<p>This is the about page.</p>
</div>
);
}
export default About;
This will create a new page at http://localhost:3000/about that displays the h1 and p tags.
Server-side Rendering
Next.js provides server-side rendering out of the box, which means that when a user requests a page, the initial HTML is generated on the server and sent to the client. This can improve the time-to-first-paint (TTFP) and the perceived performance of your application.
To implement server-side rendering in Next.js, you can use the getInitialProps function in your pages. This function runs on the server before the page is rendered and can be used to fetch data that will be used to render the page.
For example, to fetch data from an API and render it on a page, you can create a file called posts.js in the pages directory with the following contents:
import React from 'react';
import fetch from 'isomorphic-unfetch';
function Posts({ posts }) {
return (
<div>
<h1>Posts</h1>
<ul>
{posts.map(post => (
<li key={post.id}>{post.title}</li>
))}
</ul>
</div>
);
}
Posts.getInitialProps = async function() {
const res = await fetch('https://jsonplaceholder.typicode.com/posts');
const data = await res.json();
return {
posts: data
};
};
export default Posts;
This will create a new page at http://localhost:3000/posts that fetches data from the JSONPlaceholder API and renders a list of posts with their titles. The getInitialProps function fetches the data from the API and returns it as an object, which is then passed as a prop to the Posts component.
When the user requests the /posts page, the getInitialProps function will be executed on the server and the data will be fetched before the page is rendered. The initial HTML for the page will include the rendered list of posts, which will be sent to the client. When the client receives the HTML, it will hydrate the React components and enable client-side routing.
Static Site Generation
Next.js also supports static site generation (SSG), which is a technique used to generate the initial HTML for all pages at build time, rather than on the server or on the client. This can improve the performance of your application by eliminating the need to generate HTML on the server or on the client.
To implement static site generation in Next.js, you can use the getStaticProps function in your pages. This function runs at build time and can be used to fetch data that will be used to generate the initial HTML.
For example, to generate a list of blog posts at build time and render them on a page, you can create a file called blog.js in the pages directory with the following contents:
import React from 'react';
import fetch from 'isomorphic-unfetch';
function Blog({ posts }) {
return (
<div>
<h1>Blog</h1>
<ul>
{posts.map(post => (
<li key={post.id}>{post.title}</li>
))}
</ul>
</div>
);
}
export async function getStaticProps() {
const res = await fetch('https://jsonplaceholder.typicode.com/posts');
const data = await res.json();
return {
props: {
posts: data
}
};
}
export default Blog;
This will create a new page at http://localhost:3000/blog that generates the initial HTML for the page at build time and includes a list of blog posts. The getStaticProps function fetches the data from the API at build time and returns it as a prop, which is then passed to the Blog component.
When you run npm run build in your Next.js project, the static HTML for all pages will be generated and stored in the out directory. You can then deploy this directory to a static file host, such as Netlify or GitHub Pages.
Conclusion
Next.js is a powerful framework for building React applications that supports server-side rendering, static site generation, and other features out of the box. In this article, we've explored how to use Next.js with React to implement server-side rendering and static site generation, which can improve the performance of your application and provide a better user experience.
If you're new to Next.js or React, we recommend checking out the official documentation and experimenting with the code examples to get a better understanding of how these technologies work together. With the right tools and techniques, you can build high-performance web applications that are optimized for both the server and the client.