All You Need to Know about JavaScript SEO 


We need to know about JavaScript SEO. JavaScript is an essential aspect of the web platforms seeing that it provides several features that turn the website into a powerful application platform. Generally, people aren’t aware that most websites use JavaScript coding in designing their websites. 

It helps to provide better interactivity and experience to the user. JavaScript can be used for adding automatic functionality to menus, pulling products and prices, and adding animations to your text on the website. 

Websites built by JavaScript are extremely efficient, and when linked with good SEO, they can make huge profits for the organization. JavaScript-powered applications that are discovered through search engines like Google can help you acquire new users with more ease.    

This article will guide you through the essentials that you need to take care of while optimizing your JavaScript-based web pages. So let us go ahead and start by knowing, ‘What is JavaScript SEO’?


What is JavaScript SEO?

JavaScript SEO is similar to that of normal SEO and helps in making JavaScript websites easy to read and more search-friendly for users. The goal of Javascript SEO remains the same, and the primary reason for its implementation is to make your website rank higher on search engines.

Many users get scared of making content SEO friendly for JavaScript websites. Though there might be some complexities while working with such websites, it would be wrong to say that they are harder to optimize than others. 

Java-based websites are usually heavier and can affect the loading time and performance of the web page. They are mostly used to provide better functionality to the website for which you need to compromise on some other aspect of the website. 

Processing of JavaScript Pages by Google

Search engines like Google now have the power to render pages that have been built by JavaScript as long as they have accessing rights to the pages. Web Rendering Service (WRS) is a Google service that handles the rendering process of Google. The process has a simplistic approach, and the below-given diagram will help you understand it better.

Source: Ahrefs


Let us go step by step and start the process at the URL. 

  • Crawler

Crawling refers to a process in which the search engine sends its Bot to the web page to fetch its details so that they can rank the page accordingly. The work of the crawler is to send the request to the server for the header and contents of the file. 

There are several tools such as URL Inspection Tool that can help you see how Google crawls through your web pages. The request most likely comes from mobile user-agents as Google mostly uses mobile-first indexing instead of desktop indexing. 

There are a few websites that may block the external visitors on the site and hence end up blocking Google crawler.  Hence they use user-agent detection software to make their content visible to a specific crawler. 

Especially when dealing with JavaScript websites, it is a possibility that Google might be seeing something different on its end. However, to fix these issues, Google provides tools such as URL Inspection Tool,  Mobile-Friendly Test, and  Rich Results Test.

They make you view how Google is looking at your web pages so that you can re-figure them accordingly to achieve the desired optimization. Remember, Google crawl through and store all the resources such as HTML pages, CSS, Javascript files, XHR requests, and API endpoints you use to build your web page.

  • Processing

There are some specific terms that you need to know before understanding the processing of JavaScript pages.

  • Resources and Links

Google does not check and read the web pages as a normal user does. It looks for the links mentioned in the pages and also the files that help in building the website. On identifying the links, the links get stored and transferred to the crawl queue for further processing. 

The resource links that are used to build a web page such as CSS, HTML, JS, etc. are fetched by Google automatically. However, for internal and external links, <a> tag with Ahref attribute must be present for Google to successfully pull the information. So you know, internal links that are added using JavaScript are not picked until rendered.

  • Caching

Google caches all the files that it downloads, including JavaScript files, HTML pages, CSS files, etc. 

  • Duplicate Elimination

Google, when downloads the files, converts them to HTML and then sends further for rendering. Content that is redundant usually gets eliminated by Google before going to the render process. Using the app shell models, only a few code and content gets shown in HTML response. In many instances, pages start showing the same code on multiple websites. 

It causes confusion, and the pages get identified as duplicates and are stopped from going to the render process. It mostly happens with newer websites that have similar code to that of any other existing website.  

  • Restrictive Directives

Google always chooses the most restrictive statements between HTML and rendered page version when picking information from the web page. If a statement gets changed by JavaScript and is getting some type of conflict with the HTML statement, Google will pick the one which is more restrictive. Remember, no index always override the index. 

  • Render Queue

Every page that is downloaded by Google goes to the renderer, and a render queue gets generated. The problem with JavasScript SEO pages is that sometimes pages get converted into HTML, and they do not get rendered for weeks because of any small error or statement that Google is not able to pick. However, it happens only in a few cases and is not a very big concern. 

  • Renderer

Rendered can be referred to as software that helps Google to see how a user sees on his screen. Here the JavaScript is processed, and any changes made by it to the Document Object Model (DOM) are analyzed. 

Google’s web rendering service is highly efficient in studying the pages and various information such as being stateless, denying permissions, shadow DOM, and flattening light DOM. Rendering the files directly on the web is a complex procedure that needs a high amount of resources. 

Google, however, is using multiple shortcuts to get things done with efficiency and in less time. There are other websites such as Ahrefs that renders pages at a very large scale. Ahrefs renders over 150 million pages a day and also check for JavaScript redirects.  

  • Cached Resources

Google produces fast and efficient results, mostly because it is heavily relying on catching resources. Google caches files, pages, API requests, and any other information that they acquire. 

Before sending the data to the renderer, they make sure to cache it for future reference. They never download every page that is being loaded, instead, use the cached resources for speeding up their process. 

This technique is not the most reliable, as in some cases. The rendering process can go to an impossible state where the index version of the page still contains parts of the older files. 

So whenever you update your files, make sure to generate new names for them so that Google does not confuse them with the data of older files. 

  • No Fixed Timeout

There are a huge number of people that believe renderer waits for only five seconds to load your page. This is not true. As told above, Google uses cached files to generate the data. The renderer does not have any fixed timeout. It keeps trying again and again until no more network activity is detected where it stops its process.


What Does a Googlebot See?

Googlebot does not read the data as the user themselves read it. It does not have the power to click on things or scroll freely on the page. When we talk about content, if it is loaded in DOM, the Googlebot automatically reads the content. 

It just adjusts the screen height and makes the height longer than usual to study the content. You can not hide the data from DOM. If data is present in DOM, it will be read, else it will give an error message of content missing. 

When reading the data from mobile devices, it readjusts the screen size to study the data. For example, a screen size of 411×731 pixels in mobile phones will get converted to 12,140 pixels. In the case of desktop, the process is similar, and a screen size of 1024 x 768 pixels is converted into 9307 pixels. 

It will be fascinating for you to know that Google does not paint the pixels in the rendering process. It uses additional resources for the page to finish loading and leaves it right there. 

This is enough for them to understand the structure and layout of the page without the need to actually paint the pixels. The intention of rendering is to process the semantic information so that data analysis can be successfully done. 


Crawl Queue

Google needs to balance the crawling of your site with every other site available on the internet. Hence, it uses a resource known as the crawl budget. There is a specific crawl budget for every website. It helps Google in prioritizing the request for the render process. Websites that have an abundant amount of graphics or dynamic pages usually crawl slower. 


Testing and Troubleshooting of JavaScript

Websites built on JavaScript only have the ability to update some parts on the DOM. Users often navigating between the webpages do not update many aspects on the DOM, such as title or canonical tags. 

However, it is not a big problem for Google. The pages that Google loads do not have any specific state. Therefore, they aren’t using any previous file information and are not even navigating between the pages. 

Many developers take it as a serious issue when they navigate between the pages, and there is no update in the canonical tags. It can be easily fixed using the History API tool that lets you update the state of the webpage. You can use Google’s testing tools to check how Google is viewing your page. 


View-source vs. Inspect

You might have noticed this, when you right-click on a web page, you get options such as view page source and inspect. View page source shows you the information that the GET request would show. 

It can be referred to as the raw form of HTML on your web page. Whereas the inspect option gives you the processed DOM after the transitions have been made. You can say that similar data is shown to Googlebot. 

It is the most recent or updated version of the page. When you are working with JavaScript, you should prefer using inspect rather than the view source option.  


Google Cache

You can never rely entirely on the Google cache. It does not produce the same results every time. Sometime it may show information of initial HTML, and sometimes the information of rendered HTML. It wasn’t developed as a debug tool and was made to view the content in the case of a website crash or when your website is down. 


Google Testing Tools

For debugging the JavaScript of your web page, there are many efficient tools provided by Google. URL Inspector is one of those popular tools that can be found inside Google Search Console. 

Although these tools do not present the data as it is seen by Google bots, it is extremely efficient in analyzing and debugging the data. Remember, these tools use the resources from real-time and do not use the cached versions of file like the renderer generally does. 

These tools will present your data in the form of painted pixels that Google does not view in its renderer. However, you can use the tools to check if the content is DOM loaded. The tools are beneficial in making you find the blocked resources and console error messages that are helpful for the debugging process. 


Checking your Content is Displayed on Google or Not?

Take a snippet of your content and paste it on Google to check if it is presenting your data or not. You can also use a phrase from your website and search on Google to see if your data is coming on the search page or not. If the data comes, it means your content is being seen by Google. Remember, by default hidden content might not be shown on the snippet on search engines. 



Ahrefs provides access to some fantastic tools that enables you to analyze and unlock more data that be that can be studied in the audits. It has a separate option in its Ahrefs toolbar that supports JavaScript and enables the user to compare HTML and rendered versions of the tags. 

Rendering Options

Source: Ahrefs

There are numerous options available for the rendering of JavaScript. Search engines are efficient in working with different kinds of rendering, such as static rendering, SSR, and prerendering setup. 

The biggest challenge is the execution of client-side rendering, as all the rendering in this process is held on the browser itself. Although Google will still be fine with client-side rendering, you must choose any other rendering option as it will be more helpful in supporting other search engines than Google. Other browsers such as Bing, Baidu, and Yandex, also support the JavaScript rendering, but their scale is not as large as that of Google. 

Another possible option is dynamic rendering that is executed for specific user agents. It is not actually a rendering agent and is basically a walkaround. However, it may become beneficial for rendering certain search engines and social media bots. 

Remember, social media bots do not use or run on JavaScript, therefore tags like OG will not be witnessed unless they are rendered before providing the data to bots. 


How to Make Your JavaScript Website SEO Friendly?

If you are familiar with usual SEO techniques and strategies, then it is not a big issue for you to understand JavaScript SEO as the difference is minute. Let us have a look at some of the important aspects of JavaScript. 

On-Page SEO

The normal rules that you apply for regular pages still apply to JavaScript webpages. It includes title tags, content, meta descriptions, meta robot tags, alt attributes, etc. However, in the case of JavaScript, webpages, descriptions, and titles may be reused. Also, the alt attributes that are used on the images are hardly used.  


If you want your pages to rank better, make sure to change the URL every time you update the content. As previously told, the same filename many times can create confusion, and data redundancy will not let your files get rendered successfully. 

In JavaScript frameworks, a router maps you to clean URLs. It does not require the use of # for the routing process. This problem usually came in earlier versions of Angular. Anything that is written after the # gets ignored by the server.

Do not Stop the Crawling 

Google requires the data to be fetched and analyzed. If you haven’t provided your page the permissions to access the data by external sources, the site will block any external activity. This will stop Google from fetching your site information and hereby ranking it. So make sure never to block access to the resources of your webpage. 

Duplicacy in Content

Many duplicate content issues may arrive when using JavaScript SEO as various URL’s may get generated for the same content. The reason might be because of capitalization, parameters with IDs, etc. 

For example:

The solution to this problem is simple. You can choose a version of the file you want to get indexed and set canonical tags over it. 

SEO Plugin

In JavaScript frameworks, the plugins are usually denoted as modules. Also, there are multiple versions available for many popular frameworks like React, Angular, and Vue. All you have to do is search the framework plus the module name to find the needed results. Meta tags, Head, Helmet, are some of the most famous modules that allow you to set popular tags required for the SEO process. 

Lazy Loading

Lazy loading can be referred to as an SEO technique that limits the data been send to a renderer. Instead of sending all the files, it only sends data that is important and required for the process. There are various modules available for handling lazy loading

These modules work efficiently with all the different JavaScript frameworks. Suspense and Lazy are the two most popular modules used for this process. The only limitation it has is that it can’t load the images. Therefore, you will still have to use JavaScript to load the images part of the webpage. 

Error Pages

Webpages built on the JavaScript framework are different from the server-side websites, and hence their errors are also different than others. A JavaScript redirect can be used to a page that responds with error 404 status code. Or you can simply add a no-index tag when the page the user is looking for isn’t available. 


As told above, JavaScript frameworks use routers to map to clean URLs. The routers can have additional modules that can create their own sitemap. To find them, search for your system + router sitemap like Angular router sitemap. Various renderers also provide sitemap options, and the same process works for it. Add system you use + sitemap on Google, and you will get all the existing solutions for it.  


Different frameworks use different modules to support the features needed for internationalization. They are usually ported to some other destination and include intl, i18n, or numerous times the same modules that are used for header tags. Hreflang is an example of internationalization. 


Server-side SEO uses 301/302 redirects. JavaScript is usually run as a client-side. Hence Google processes the page that comes from the redirect. The redirects can be generally found in the code form on window.location.href.


Wrapping Up

JavaScript provides an excellent opportunity to make your website more dynamic and user friendly. Creating SEO-friendly pages that are designed in JavaScript is not a tough process. You only need to have a little more information to successfully make your JavaScript pages SEO friendly. If you have a good knowledge of traditional SEO, then implementing new techniques and strategies won’t be a big challenge for you.