The benefits of dynamic rendering on the SEO

In recent years JavaScript frameworks have become increasingly popular, thanks in large part to the flexibility they offer: despite the progress, however, when search engine crawlers visit scripted websites like AngularJS, React, Vue.js or jQuery it is possible that they do not “see” content like browsers actually do afterward, and this can cause indexing problems or even worse. There are, however, some ways to better communicate the site and bots, and especially the technique of dynamic rendering seems to offer the best answers to translate the content and structure of the site in the language preferred by crawlers.

What is dynamic rendering

Dynamic rendering is an exclusive pre-rendering for search engine robots: while regular site visitors are served normal client-side rendered content, crawlers receive a static HTML version of the pages, served in server-side rendering.

It is, therefore, a system that allows a different visualization of the site based on the type of user agent that performs the call, distinguishing between the normal client-side version of the site for users and the one designed specifically for Googlebot, Bingbot and other bots, which can then access, scan and index content without running JavaScript.

History of dynamic rendering

The concept of dynamic rendering was officially introduced by Google in 2018, although many sites were already adopting similar techniques through self-produced solutions or using third-party software: at the Google I/O conference in 2018, John Mueller defined dynamic rendering as “the principle of sending users normal client-side rendered content and sending fully server-side rendered content to search engines”.

Bing has also started to suggest this practice, proving how dynamic rendering can be a useful solution for a “historical” problem such as rendering and, in particular, the execution of some JavaScript frameworks.

Although search engines like Google and Bing can process JavaScript, in fact, they face limitations in trying to do so on a large scale; moreover, Google’s HTML crawler is not always able to process JavaScript, and then Googlebot can put such a page in a queue, waiting for the rendering resources to become available to render the whole page – and this also applies to Bingbot.

Google’s recommendation: use dynamic rendering as a temporary solution

However, we must emphasize an important point, also highlighted by a recent update of Big G’s official documentation to this technical aspect: for Google, dynamic rendering is an alternative solution to the problems of crawling and indexing Google Search with JavaScript, and therefore not the definitive and recommended method, because it generates additional complexity and requires more resources.

In fact, this is the position Google has taken from the beginning, but it was necessary to reiterate and mark it more sharply after the constant advances in Web and crawling technology (and the ever-increasing use of JavaScript), to try to convince developers, webmasters, and SEOs to implement alternatives to dynamic rendering, i.e., server-side rendering, static rendering, or hydration. In these cases, in fact, all meaningful content is displayed on the Web site’s server, and both users and bots receive a fully loaded page without the need to request additional resources.

How dynamic rendering works and what sites it serves

Dynamic rendering is not needed by all sites, therefore, but it is a possible alternative solution for those hosting pages with public indexable content generated with JavaScript that changes rapidly or uses JavaScript features not supported by major crawlers.

JavaScript rendering is user-friendly, but not bot-friendly, especially when crawlers are faced with large Web sites, because there are still limitations to processing JavaScript at scale while minimizing the number of HTTP requests.
Implementing this mode therefore has the advantage of overcoming this, as it allows search engine bots to access content without having to render it.

Differences with client-side rendering

In talk at SMX Next, Nati Elimelech (Wix’s tech SEO lead) provided an overview of how JavaScript