The impact of Javascript on SEO in 2024

In the dynamic world of search engine optimization, it is essential to understand how search engines interact with modern technologies such as JavaScript. This is especially important for marketing managers and CMOs who want to make sure their Web sites perform optimally in search results. This introduction provides insight into how search engines process JavaScript and emphasizes the importance of an accessible Web site structure.

Understanding how search engines process JavaScript

It is essential to understand how search engines, such as Google, crawl and index JavaScript. The impact of this on the visibility of JavaScript-based content in search results is significant. Google has significantly improved its approach to handling JavaScript over the years.

Now it is possible for Google to crawl and render JavaScript content. This means that the search engine sees the content as a user would. However, this process is more complex than crawling static HTML and can lead to visibility problems if not adequately managed. For more in-depth information, it is advisable to consult Google’s own explanation of their search mechanisms.

How does Googlebot discover new pages?

The process of crawling and indexing by Google is crucial for making Web pages visible in search results. Here is a description of this process:

  1. Crawling:
    • starting point: Google starts with a list of known URLs from previous crawls and sitemaps submitted by website owners.
    • Googlebots: These are Google’s “crawlers” or “spiders” that explore the Web. They visit Web pages, follow links and discover new or updated pages.
  2. Indexing:
    • Page processing: After crawling, Google processes page content, including text, images and videos.
    • Index creation: The processed information is stored in Google’s index, a large database of all found information.
    • Use of keywords: Google identifies keywords on the page to understand what it is about.
  3. Ranking and retrieval:
    • Using the index: When doing a search, Google uses this index to find relevant results.
    • Ranking: Pages are ranked based on various factors such as relevance and site quality.
  4. Continuous process:
    • Regular updates: Google’s crawlers visit sites regularly to find updates and new content.
  5. Challenges with JavaScript:
    • Crawling JavaScript: Sites with a lot of JavaScript can pose challenges for Googlebots.
    • Solutions: Google has improved its ability to handle JavaScript, but it is still important to make essential content and links accessible in the HTML.

This process ensures that Google can provide the most relevant information based on search queries and emphasizes the importance of SEO optimization for effective indexing. This is what this looks like in an image:

How does Googlebot discover new pages

Importance of an accessible website structure

An accessible website structure is a fundamental aspect of web accessibility, which also plays a crucial role in SEO. It is important to keep the basic structure of the site accessible even when JavaScript is not loaded or disabled.

This ensures that search engines can effectively crawl and index the content. This aspect is of particular importance, as some search engines and Web crawling tools have difficulty handling JavaScript. Maintaining an accessible structure increases the likelihood that content will be indexed and positioned correctly in search results.

Server-side, client-side or dynamic rendering: a choice for SEO

In the world of web development and SEO, the choice between server-side and client-side rendering plays a crucial role. This introduction highlights the differences and impact of both methods on a website’s SEO performance. Please also refer to my extensive article for this purpose.

Server-side rendering

With server-side rendering, the entire page loads on the server before it is sent to the browser. This facilitates crawling and indexing by search engines, which is beneficial for SEO. This includes the traditional model of loading a new page with each click. While this is beneficial for search engine visibility, it can sometimes result in slower loading times for the user, especially for complex websites.

Client-side rendering

In the case of client-side rendering, the rendering of the page is done in the user’s browser, usually through JavaScript. This often results in faster load times because less data is exchanged between server and browser.

Single-page applications (SPAs) are a good example, where content changes dynamically without reloading the page. However, this can present challenges for SEO, as search engines may have difficulty correctly indexing this dynamically loaded content.

Dynamic rendering

Dynamic rendering combines server-side and client-side methods. Depending on the user, whether a person or a search engine bot, the server chooses server-side or client-side rendering. This is especially useful for complex sites where both a fast user experience and good SEO are important. However, it requires more complex implementation and maintenance.

Dynamic content and its impact on SEO

Understanding how search engines see and index dynamic content generated by JavaScript plays a key role in SEO strategies. JavaScript is often used to create interactive elements on Web pages. However, if this content is not rendered correctly for search engines, it can lead to indexing problems. This can mean that valuable, interactive content remains invisible in search results.

Take, for example, a product catalog that loads dynamically via JavaScript. If this content is not accessible to search engines, either in source code or through server-side rendering, these products may remain invisible in search results.

To avoid this, it is essential to ensure that dynamic content remains accessible to search engines. This can be done by implementing dynamic rendering or by keeping key content and navigation always accessible even when JavaScript is disabled. This ensures that the content is not only user-friendly, but also SEO-friendly.

The influence of the various JS frameworks

In today’s Web development, JavaScript frameworks play a crucial role in the construction and functionality of Web sites. However, each framework has its unique impact on SEO, an aspect essential to online visibility and user experience. This introduction highlights the impact of various JavaScript frameworks on SEO, an important consideration for Web developers and marketers.

The influence of the various JS frameworks

The impact of Angular on SEO

Angular, known for its power, presents SEO challenges through its client-side rendering. This can cause problems when crawled by search engines. However, with server-side rendering via Angular Universal, these challenges can be overcome, making content more accessible to search engines.

The impact of React on SEO

React, popular for creating dynamic user interfaces, is primarily client-side and may face the same SEO challenges as Angular. Techniques such as server-side rendering, for example with Next.js, help make content more SEO-friendly.

The impact of Vue.js on SEO

Vue.js is both flexible and lightweight, but like other client-side frameworks it can cause SEO problems if not managed properly. By using server-side rendering or pre-rendering, the SEO performance of a Vue.js application can be improved.

The impact of Ember.js on SEO

Ember.js follows a convention-over-configuration approach and has built-in server-side rendering capabilities with FastBoot, which contributes to improved SEO friendliness.

The impact of Backbone.js on SEO

Backbone.js is a more minimalist framework and offers less direct SEO solutions compared to other frameworks. This requires more manual configuration and optimization for better SEO.

The choice of a framework depends on the ability to implement server-eside or dynamic rendering, essential for better search engine visibility.

The Javascript frameworks at a glance

Here is an overview of the five JavaScript frameworks, with their SEO challenges and solutions:

FrameworkChallenges for SEOSolutions for SEO
AngularClient-side rendering can make crawling difficult; requires server-side rendering for better SEO.Server-side rendering with Angular Universal.
ReactPrimarily client-side, may have the same SEO challenges as Angular without server-side rendering.Server-side rendering techniques such as Next.js.
Vue.jsMay cause SEO problems with purely client-side use; improvement possible with server-side rendering.Use of server-side rendering or pre-rendering.
Ember.jsProvides built-in server-side rendering with FastBoot, which is more SEO-friendly.Use of convention-over-configuration approach and FastBoot.
Backbone.jsMinimalist and requires more manual SEO optimization; fewer out-of-the-box solutions.Manual configuration and optimization for SEO.
Javascript frameworks and the impact on SEO.

This table provides a quick overview of the challenges and solutions related to SEO for each of these popular JavaScript frameworks.

Tools and techniques for JavaScript SEO testing

To optimize JavaScript-based websites in search engines, using the right tools and techniques is essential. These tools provide insight into how search engines index and display JavaScript content, which is crucial for effective SEO.

Google Search Console

The Google Search Console is indispensable for monitoring page indexing and identifying any crawl errors. It provides valuable data about the site’s search performance, allowing for quick action to improve SEO.

URL inspection in Search Console

The URL inspection feature, formerly known as Fetch as Google, is ideal for checking that JavaScript content is loaded and displayed correctly by Google. This provides direct insights into the search engine accessibility of specific pages.

Lighthouse

Google’s Lighthouse is a versatile tool that helps analyze the performance, accessibility and SEO of Web pages. It provides detailed reports that point out areas for improvement, which is essential for fine-tuning the website.

Tools and techniques for JavaScript SEO testing

Screaming Frog SEO Spider

This desktop application is excellent for crawling websites to quickly identify SEO issues. It simulates how search engines crawl a site, giving insight into potential content indexing problems.

JSDOM

JSDOM in node.js allows users to test a simulated, JavaScript-rich environment of Web pages. This is crucial for ensuring that all elements load correctly and are accessible to search engines.

The tools at a glance

Here is a table that lists the pros and cons of different tools for testing problems with JavaScript and SEO, along with a score from 1 to 100 on how interesting each tool is for this purpose:

ToolAdvantagesConsScore (1-100)
Google Search ConsoleMonitoring indexing, identifying crawl errors, understanding search performanceCan be overwhelming for new users, offers no immediate solutions90
URL inspection in Search ConsoleVerifies that JavaScript content is loaded and displayed correctly by GoogleFocusing only on how Google sees pages may be limited in scope85
LighthouseAnalyzes performance, accessibility and SEO, provides detailed reportsTechnical in nature, requires some knowledge to interpret the data80
Screaming Frog SEO SpiderSimulates how search engines crawl sites, identifies SEO issuesPaid tool, can be complex to use75
JSDOMTest a simulated JavaScript environment, ensures correct loading of elements for search enginesRequires technical knowledge, aimed more at developers70
Tools for Javascript and SEO.

These scores are based on the effectiveness of each tool in identifying and solving problems with JavaScript and SEO.

Conclusion

Properly deploying JavaScript and maintaining an accessible website structure are crucial to an effective SEO strategy. By having a good understanding of how search engines interact with JavaScript, marketers can make more informed decisions that contribute to their website’s visibility and findability. In a competitive digital landscape, this is not only desirable, but necessary for online success.

Senior SEO-specialist

Ralf van Veen

Senior SEO-specialist
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I have been working for 10 years as an independent SEO specialist for companies (in the Netherlands and abroad) that want to rank higher in Google in a sustainable manner. During this period I have consulted A-brands, set up large-scale international SEO campaigns and coached global development teams in the field of search engine optimization.

With this broad experience within SEO, I have developed the SEO course and helped hundreds of companies with improved findability in Google in a sustainable and transparent way. For this you can consult my portfolio, references and collaborations.

This article was originally published on 7 December 2023. The last update of this article was on 28 December 2023. The content of this page was written and approved by Ralf van Veen. Learn more about the creation of my articles in my editorial guidelines.