Hubert
7 min
October 17, 2024

Learn about server-side rendering in React

Server-side rendering (SSR) in React is useful for building dynamic, high-performance web applications. With SSR, the user interface is generated on the server, which speeds up page loading and gives users more control over what is displayed. In this article, we will discuss the benefits of SSR in React, how it works, and the challenges of implementing it in existing projects.

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Learn about server-side rendering in React

What is server-side rendering?

Server-side rendering (SSR) is a technique for rendering web pages on the server side before they are sent to the browser. Unlike Client-Side Rendering (CSR), where the browser builds the page from data provided by the server, SSR generates all the HTML on the server. This makes the page load faster, which benefits users with slower internet connections or older devices.

SSR improves performance and SEO because the server provides the finished HTML. This makes it easier for search engine robots to index the content correctly. With CSR, dynamically generated content can be more difficult to index. SSR also provides greater application performance consistency across browsers, eliminating issues with support for specific features.

Although SSR requires more infrastructure and is more complex to implement, it offers tangible benefits, especially for applications that require fast loading and SEO optimization.

How does server-side rendering work in React?

Server-side rendering (SSR) in React renders application components on the server before they are uploaded to the user’s browser. Instead of relying on the browser to execute JavaScript and dynamically build the user interface, the server renders the finished HTML immediately delivered and displayed in the browser when the page loads.

A technical discussion of the SSR process

  • A request to the server: When a user opens a page, a request is sent to the server hosting the React application.
  • Rendering the component: The server uses React to render the application components in HTML. The server downloads and uses all the data needed to render the page.
  • Sending HTML to the client: The finished HTML is sent to the browser, making the page instantly visible.
  • Hydration: Once the HTML is uploaded, the React application activates the page’s interactive features, executing JavaScript code in the browser so that the components can respond to the user’s actions.

Benefits of using SSR in React applications

Server-side rendering in React offers many benefits that translate into better application performance and a better user experience. Here are the key ones:

Content personalisation:

SSR enables the dynamic delivery of content tailored to user preferences, such as language, location, or preferences. This results in more personalized interaction and better-tailored content.

Incremental content loading (lazy Loading):

With SSR, critical elements of a page can be loaded immediately, and less relevant sections can be loaded later. Lazy Loading improves responsiveness and reduces wait times for displaying the most critical information.

Streamline application state management:

The server uploads the initial state of the components, allowing the fully configured application to be displayed immediately on the client side. This provides instant gratification, minimising launch delays and errors.

Improved SEO optimization:

SSR significantly improves search engine visibility. The server delivers the finished HTML to the browser, making it easier for indexing robots to read the page’s content, increasing the chances of higher rankings in search results. 

Challenges and limitations of server-side rendering

While server-side rendering (SSR) in React offers many benefits, it also presents several challenges:

  • Application state management: SSR requires state synchronization between server and client. The hydration process that makes the page interactive as it loads can be challenging to manage, especially in more complex applications.
  • Server load: Each user request requires the generation of full HTML, which increases the load on the server, especially if there is a lot of traffic. To reduce this problem, it is necessary to implement caching.
  • Cache optimization: Cache management in SSR is more complicated. You need to balance loading speed with content timeliness.
  • Integration with existing projects: Adding SSR to applications that have been using CSRs may require significant architectural redesign. This task, while challenging, is a necessary step towards leveraging the benefits of SSR, and it’s important to be prepared for the increased development time.
  • Time and complexity: SSR increases the application’s complexity, which can affect the development time and cost, as well as the project’s maintenance.

Popular tools and libraries that support server-side rendering in React

Server-side rendering (SSR) in React can be supported by several popular tools and libraries that simplify the implementation of this technique. 

Next.js is one of the most popular tools for simplifying the implementation of SSR in React applications. It allows pages to be dynamically rendered on the server and provides functions such as getServerSideProps, enabling data to be fetched from the server before rendering. Next.js is ideal for building SEO-friendly applications and those that require dynamic content.

Gatsby also supports SSR. This tool is best suited for creating sites with many fixed elements, such as blogs or news portals, where much of the content can be generated in advance, and the dynamic components can be loaded using SSR.

Razzle is a more flexible tool with fewer constraints than Next.js and Gatsby but requires more advanced configuration. It is often used in projects that require custom webpack configuration and complete control over the application building process.

The choice of tool depends on the project’s needs. Next.js is best for general SSR applications, Gatsby for fixed-content sites, and Razzle for projects that require flexibility and customization.

Best practices for implementing SSR in React

When implementing server-side rendering (SSR) in React, several best practices should be followed to optimize the application’s performance and scalability.

  • Minimise requests to the server: Limit the number of requests the server has to handle during rendering. Retrieve critical data once, and cache less frequently changing information to reduce server load and speed up page loading.
  • Use caching: Cache server responses and resources to reduce unnecessary requests and speed up content delivery to users. Ensure that caching mechanisms are properly configured to deliver up-to-date data.
  • Data prefetching: Try to prefetch the data you need before a user requests more pages. This will minimize the time it takes for the following pages to load.
  • Application scaling: Use techniques such as load balancing and dynamic server scaling for larger applications. This will help to spread the load and ensure that your application runs smoothly as the number of users increases.

Alternatives to server-side rendering

There are many ways to render web pages, and SSR is only one of them. What are the others?

Static Site Generation (SSG) generates static pages at application build time. This ensures that sites are delivered more quickly. They are already ready to be viewed, which significantly improves performance. SSG works best for sites with infrequently changing content, such as blogs or documentation.

Incremental Static Regeneration (ISR) combines the benefits of SSG and SSR. It allows individual pages to be regenerated in real-time, allowing content to be updated without rebuilding the entire application.

SSG and ISR are more efficient and scalable than SSR but less flexible. The first tool will work best for applications that require immediate content updates.

SSR use cases in React applications

SSR works particularly well where load speed, SEO, and dynamic data are critical. For example:

E-commerce:

SSR is ideal for online stores where fast-loading product pages and dynamic content updates are key. With SSR, users can browse offers more quickly, which has a positive impact on their experience and also improves SEO performance.

News sites:

For news sites, fast access to content is a priority. With SSR, the page loads instantly and is more easily indexed by search engines. This is critical for SEO and user satisfaction, especially on slower connections.

Social media platforms:

SSR ensures that content is displayed quickly for platforms with dynamic content, such as comments or user updates. Accessibility is critical to user engagement.

Summary

Server-side rendering (SSR) in React improves performance and SEO, especially for e-commerce applications and news sites. SSR dynamically renders content but requires more server resources and complex application state management.

Tools that support SSR include Next.js and Gatsby. SSR is worth implementing where load speed and SEO optimisation are important, as it results in a better user experience.

FAQ

Is SSR faster than CSR?

SSR typically loads the first page faster, especially on slow internet.

How do I convert React to server-side rendering?

Use a framework like Next.js that has built-in support for SSR.

Does Next.js support SSR?

Yes, Next.js has native support for SSR.

Do hooks work in SSR?

Yes, hooks can run in SSR, but some, like useEffect, only run on the client side.

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