When building modern web applications with Next.js, selecting the right rendering technique is critical for optimal performance and a smooth user experience. Next.js has three main rendering options: client-side rendering (CSR), server-side rendering (SSR), and pre-rendering.
Each approach has unique characteristics, advantages, and limitations:
| Feature | CSR | SSR | Pre-rendering |
| Rendering process | Content rendered in the browser using JavaScript | Content rendered on the server and sent to the browser | HTML generated at build time served as static |
| SEO | Can be challenging for SEO | Reasonably good for SEO, content available to crawlers | Excellent for SEO, fully rendered HTML upfront |
| Dynamic content | High flexibility for dynamic content | Balanced performance and flexibility | Less flexible, requires rebuilds for dynamic updates |
| Development complexity | Easier to develop, mainly focuses on the client-side logic | Higher complexity, as developers need to manage both server-side and client-side logic | Lower complexity during runtime but requires managing the build process and handling dynamic updates |
| Use cases | Best for highly interactive, real-time web apps like SPAs (single-page applications) | Ideal for content-driven sites or apps needing fast initial load and good SEO, e.g., blogs, news sites | Great for static or infrequently updated content, like landing pages or documentation sites |
Deciding which technique to use can significantly impact your application’s speed, SEO performance, and scalability. In this article, we’ll examine each rendering method in detail, exploring their use cases, and providing examples to help you understand when to leverage each. By the end, you’ll clearly understand which best aligns with your development goals, allowing you to maximize your application’s performance and user experience.
Let’s jump in!
Before frameworks like React, Vue, and Next.js, most website content was rendered on the server and sent to the browser as static HTML. While this approach worked, it severely limited interactivity, making it challenging to build highly dynamic pages such as analytics dashboards. Client-side rendering (CSR) changed this by shifting the rendering process to the browser using JavaScript.
In CSR, the browser initially requests a single HTML file, which serves as the entry point for the application. This file includes links to the necessary JavaScript files that handle rendering the content and requesting any additional data needed. This process allows for more interactive, dynamic user experiences because content updates happen directly in the browser without reloading the entire page.
In Next.js, CSR is no longer the default rendering strategy. This is due to the recent shift in the ecosystem of pre-rendering content on the server with React Server Components (RSC) and server-side rendering (SSR) – concepts we’ll explain in a bit. To render a client-side component, we must lazy load it using the exported dynamic function with the ssr option disabled:
"use client";
import dynamic from "next/dynamic";
const Header = dynamic(() => import("../components/header"), {
ssr: false,
});
An alternative to CSR is server-side rendering (SSR), which is a web development technique in which the server generates the HTML content of a webpage and sends it to the client’s browser. Unlike client-side rendering (CSR), where JavaScript on the client side dynamically renders the content, SSR pre-renders the HTML on the server before sending it down to the browser as HTML.
This means the browser receives the fully rendered HTML content and doesn’t have to wait for JavaScript to render the initial content.
In Next.js, SSR is the default rendering strategy. You do not have to do anything special to render a component server-side.
Now, Next.js uses a relatively new terminology called ‘Client’ and ‘Server’ components, or ‘React Server Components‘. To put it simply, this enables you to execute asynchronous code exclusively on the server inside components.
I bring this up because there’s another misconception that ‘Client-side’ components aren’t rendered on the server. This is false. Next.js renders all components on the server by default unless you disable ssr explicitly.
To create a server-side rendered component, all you have to do is simply create the component and export it. Next.js will take care of the rest:
import React from "react";
export const Page = () => {
const isServer = typeof window === "undefined";
console.log(isServer ? "Server" : "Client");
return <h1>HelloWorld</div>;
};
Pre-rendering is a technique where static HTML files are generated at build time, meaning the HTML for a given page is created before any request is made by the user. This HTML is served directly to users when they visit the site, offering a balance between server-side rendering (SSR) and client-side rendering (CSR).
In contrast to SSR, which renders HTML dynamically on each request, pre-rendering generates the HTML once during the build process. This HTML is then cached and reused, reducing server load while providing fast initial page load times, similar to SSR.
However, because the pages are rendered in advance, there is a potential for serving outdated or “stale” content with pre-rendering. You can circumvent this by using a free tool like Prerender.io that refreshes the cache on its own after some time.
Next.js supports pre-rendering out of the box with its getStaticProps function, which allows pages to be pre-rendered at build time. Here’s an example:
Learn more →// pages/index.js
import React from 'react';
const HomePage = ({ data }) => {
return (
<div>
<h1>Prerendered Page</h1>
<p>Data fetched at build time:</p>
<pre>{JSON.stringify(data, null, 2)}</pre>
</div>
);
};
// This function is called at build time
export async function getStaticProps() {
// Fetch data from an API
const res = await fetch('https://jsonplaceholder.typicode.com/posts');
const data = await res.json();
// Pass data to the page component via props
return { props: { data } };
}
export default HomePage;
getStaticProps and getStaticPaths, enabling efficient pre-renderingnuxt generateWhen to choose client-side rendering:
When to choose server-side rendering:
When to choose pre-rendering:
A hybrid approach that combines CSR, SSR, and pre-rendering may be the best solution for many projects. Frameworks like Next.js allow developers to use a mix of these rendering techniques for different pages or components within the same site. For example, you can pre-render static marketing pages, use SSR for dynamic product pages, and implement CSR for interactive features like user dashboards.
This hybrid model allows you to optimize performance and SEO for content-driven pages while still enabling dynamic, real-time interactivity for user-driven features. It gives you flexibility in balancing the benefits of each rendering approach based on your project’s specific needs.
Choosing the right rendering technique for your Next.js application — whether it’s client-side rendering (CSR), server-side rendering (SSR), or pre-rendering — depends largely on your project’s requirements for performance, SEO, and content dynamism.
CSR is ideal for highly interactive, real-time applications but can pose challenges for SEO. SSR balances fast initial load times with good SEO performance, making it a great option for content-heavy websites. Pre-rendering excels in scenarios where static content is preferred and offers the best SEO and performance benefits but requires maintenance for frequently changing content.
Each rendering technique has its own strengths and trade-offs, and Next.js’s flexibility allows you to combine these approaches based on the needs of different components or pages within your application. By carefully considering your project’s goals, user experience, and performance needs, you can choose the optimal rendering strategy or hybrid approach, ensuring that your application delivers the best experience for users and search engines.
Debugging Next applications can be difficult, especially when users experience issues that are difficult to reproduce. If you’re interested in monitoring and tracking state, automatically surfacing JavaScript errors, and tracking slow network requests and component load time, try LogRocket.
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