Published on January 18, 2024

Explaining the Difference Between Prerendering and Other Rendering Options

The many terminologies in web development can be overwhelming. Yet, to choose the best solution for your website’s success, you need to know what rendering processes are available, how they differ when processing JavaScript content, and their impact on SEO performance.

This blog will compare various rendering types, helping you choose the ideal JavaScript tool for your website.

What is Rendering?

Rendering is the process of interpreting and displaying website code (HTML, CSS, and JavaScript) into visual output, such as the website’s layout, colors, fonts, and animations.

This process usually happens in real time whenever users access a web page. For each user interaction, the page will be re-rendered to update the displayed content.

There are different types of rendering, and the most common ones include:

Static rendering
Static rendering is the process of prerendering content into static HTML files before users request them. This typically takes place during the build or deployment period of a website. It also means that the created static HTML files won’t change until the next build or update.

Server-side rendering (SSR)
As the name suggests, the rendering process (generating a full HTML page) of server-side rendering (SSR) occurs on the server when a user agent requests a particular web page. The browser only receives ready-to-display content, allowing users to see the page without additional processing on their device.

Client-side rendering (CSR)

Unlike SSR, the rendering for CSR happens on the browser, typically in response to user interaction. Hence, the name is client-side rendering. The browser only receives a minimal HTML page from the server. To display the full web page, JavaScript will be used to fetch and process any additional elements. 

Rehydration

Rehydration happens after the initial HTML and JavaScript have been loaded on the client side. The JavaScript loops back into the HTML, ensuring the page stays interactive and dynamic.

Another rendering type you may also have heard of is prerendering. This will be discussed in the next section.

What is Prerendering?

Prerendering is a technique where the static version of a web page is generated and cached in advance at build time or during runtime. These pre-built pages are stored and served whenever a user agent requests them.

The definition of prerendering above may sound similar to static rendering; that’s because prerendering is a subset of static rendering. They’re both aimed to serve pre-generated static HTML files to improve website performance.

Prerendering is often associated with dynamic rendering. Dynamic rendering is a process of serving content based on the user agent requesting it. The rendering process usually happens on-demand, providing static HTML for bots and dynamic JavaScript pages for users. 

To implement this, your servers must be capable of distinguishing between human users and bots, caching the fully rendered page versions, and executing the rendering process. 

Prerendering is best combined with single-page applications (SPAs) and client-side JavaScript frameworks. The goal of prerendering is to achieve fast PageSpeed (leveraging the static site delivery) while still providing a dynamic user experience.

Related: Optimize SPA for crawling and indexing by following this guide.

Here’s the comparison of prerendering, SSR, static rendering, and hydration in detail.

Prerendering vs. other types of rendering compared in a table format.

How Does Prerendering Affect JavaScript SEO?

Compared to static HTML files, crawling and indexing JavaScript-based content is more complex and resource-heavy. Search engine bots can’t directly index JS dynamic content. 

The content first needs to go through the rendering process before indexing. This is why many heavy JS-based websites adopt a workaround, such as prerendering.

Related: Learn how Google crawls and indexes JavaScript content.

Through prerendering, JS content is rendered into its static HTML version in advance. So, when Googlebot requests it, it can seamlessly index the content. Not only does this ensure that every page element (including the vital SEO elements) is indexed perfectly, but it also cuts the crawling and indexing time in half.

Furthermore, JavaScript is known for slowing down the page response time, compromising functionality, user experience, and technical SEO performance. Because the pre-rendered pages are cached, whenever a request is made, the page doesn’t have to load from scratch. Consequently, it improves a website server response time (SRT), an SEO metric and component of PageSpeed (a Google ranking factor).

In addition, prerendering also improves the following Core Web Vital scores, a set of crucial technical SEO metrics:

  • Faster LCP (Largest Contentful Paint)
    When users access a page, they receive ready-to-serve static files, leading to quicker rendering and improved LCP metrics.
  • Shorter FID (First Input Delay)
    Since the browser has less work to do on the client side, it can quickly display the page and respond to user interactions without needing additional processing. Consequently, the FID is improved.
  • Better CLS (Cumulative Layout Shift)
    Because the content isn’t generated per request, it minimizes layout shifts, leading to better CLS.
  • Lower TTFB (Time to First Byte)
    There is less data fetching required in static rendering pages, resulting in reduced server load and improved TTFB, which contributes to faster page loading times.

Now, what are the available prerendering solutions?

As an enterprise SEO rendering solution trusted by 65k developers and marketers across the globe, Prerender is an excellent choice.

This JavaScript SEO tool renders heavy JavaScript pages into static HTML files within seconds. 

Then, the tool will feed this ready-to-crawl content to the search engine bot, facilitating a seamless crawling and indexing process. As for requests from human users, they are redirected through the standard server routes, allowing them to enjoy the interactive JS web elements.

With a prerendering tool like Prerender, you’ll have the best of both worlds: an optimized JavaScript SEO website for crawlers and an excellent web experience for users! 

Solve JavaScript SEO Issues with Prerendering

Understanding the differences between various rendering processes, what prerendering is, and how prerendering can address the JavaScript SEO challenges can help you make informed decisions in improving your website performance.

Compared to standard SSR, hydration, and static rendering, prerendering comes with more benefits. For starters, you don’t need to change your tech stack to install Prerender. As a plug-and-play solution, it requires near-zero development time and costs. And when your website demands more prerendering service, we grow with you. Simply contact us to adjust your plan.

Prerender helps you balance healthy SEO scores and an immersive user experience—a smart solution to fix enterprise SEO rendering issues. 
Start with Prerender today!

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