JavaScript SEO: Solving Complex Rendering Issues at Scale

What is JavaScript SEO?

JavaScript SEO is a branch of technical SEO that focuses on ensuring websites utilizing JavaScript are easily discoverable, crawlable, and indexable by search engines. 

As modern websites increasingly rely on JavaScript to create dynamic and interactive user experiences, it's essential to optimize these sites so that search engines can effectively process and rank their content. 

This involves implementing best practices such as server-side rendering, proper link structures, and efficient loading strategies to enhance both search engine visibility and user engagement. 

Does JavaScript Affect SEO?

Yes, using JavaScript can impact your website’s SEO and performance in important ways.

JavaScript adds complexity, making it harder for Google to crawl, render, and index your pages compared to plain HTML. If your site relies heavily on JavaScript without proper planning, it could hurt your indexing and visibility on search engines.

On top of that, unoptimized JavaScript can slow down your site, leading to a poor user experience. A slow website not only frustrates visitors but also affects your SEO rankings.

To avoid these issues, it's essential to optimize your JavaScript and ensure your site is user-friendly and search-engine-friendly.

How to find JavaScript SEO Issues

Identifying JavaScript SEO issues is crucial to make sure that search engines can effectively crawl, render, and index your website's content. 

Though it's easy to spot websites built with JavaScript frameworks, finding specific pages or elements that change dynamically can be tricky. That's where the right website audit tool comes in handy.

Here's how you can detect and address these issues:

1. Utilize Google Search Console

Google Search Console is a free tool that helps website owners understand how their site interacts with Google Search. It offers features like the URL Inspection Tool, which provides detailed information about how Google views a specific page. 

You can check the page's rendered HTML, see a screenshot of what Google sees, and review any resources that didn’t load or JavaScript errors. This insight is crucial for identifying and resolving issues that might prevent your content from appearing in search results.

Another valuable feature is the Page Indexing report, which shows the indexing status of all your site's pages. It categorizes pages into groups like 'Indexed,' 'Error,' and 'Excluded,' helping you quickly identify and address problems that could affect your site's visibility. 

2. Compare Raw and Rendered HTML

When a browser loads a webpage, it starts with the raw HTML provided by the server. JavaScript can then modify this HTML, adding or changing content to create the final version that users see, known as the rendered HTML. 

Comparing the raw and rendered HTML helps identify these changes, ensuring that important elements like titles, meta descriptions, and links are correctly displayed to both users and search engines.

Tools like the "View Rendered Source" Chrome extension make this comparison easier. This extension displays the original HTML, the rendered HTML, and highlights the differences between them. For example in the following image, you can spot the difference between the both:

Examining these differences can help you spot any issues where JavaScript might be affecting the visibility of key content, which is crucial for effective SEO.

3. Conduct Crawls with SEO Crawlers

Conducting crawls with specialized SEO tools helps uncover JavaScript-related problems that might prevent search engines from fully understanding a website. 

Tools like Screaming Frog SEO Spider, and Sitebulb can be configured to enable JavaScript rendering. This lets them observe how pages load content and detect any breakdowns that block critical information. 

For example, Sitebulb uses the same Chromium renderer as Google, so you can see exactly how your web pages are rendered. It gives useful insights into which pages or elements are created or updated with JavaScript. This helps you spot any content that Google might not access properly. You can then share these issues with a developer to fix them efficiently.

Conducting crawls with SEO crawlers makes it easier to see where scripts may slow down page performance or restrict access to important details. This allows quick fixes to ensure search engines can accurately crawl and index the site.

The Most Common JavaScript SEO Issues

Now that you know some great tools for checking JavaScript SEO in both raw and rendered HTML, let’s talk about what to watch out for. Below, we’ll discuss common JavaScript problems that can directly impact your website’s SEO.

1. Blocked JavaScript and CSS Files

For search engines to understand your website properly, they need access to all necessary resources, like internal and external files. If your site isn’t displayed as it should be, Google may misinterpret it, showing the page differently to users and search engine bots.

One common mistake is blocking essential files in your robots.txt file.

Files like JavaScript (JS) and Cascading Style Sheets (CSS) are crucial for rendering your site and should not be blocked from Googlebot. If these files are restricted, it can affect how bots process and index your content.

But, how can you fix this? Here are some simple solution:

• Use the URL Inspection Tool in Google Search Console to see how Google views your pages. Test a few key URLs from each section of your site, especially those with unique templates.
• Check if blocked resources are essential for adding significant content to your pages. If they are, they need to be crawlable.
• Review your robots.txt file to ensure directories containing critical assets aren’t blocked. If they are, remove these restrictions.

This simple review can make a big difference in how search engines understand and rank your website.

2. Using Non-HTML Links

When building websites, it's essential to use standard HTML links—specifically, the <a> tag with an href attribute—to connect different pages. These links are easily recognized and followed by search engines like Google, enabling them to navigate your site and index its content effectively. 

However, if you create links using JavaScript functions or other methods that don't include the proper <a> tags, search engines may struggle to find and index those pages. This can lead to parts of your website being overlooked in search results, reducing visibility and potentially affecting your site's performance.

For example, if your website uses buttons or scripts to handle navigation without incorporating standard HTML link elements, search engine crawlers might not detect these pathways. This oversight can prevent important pages from being indexed, making them invisible to users searching for relevant content. 

Google's guide shows examples of incorrect implementations. Here are examples of links that Google cannot parse:

Therefore, to ensure all your pages are discoverable, it's best to use traditional HTML links for navigation.

3. Client-Side Rendering Issues

Modern JavaScript frameworks like React, Angular, and Vue often use client-side rendering (CSR) by default. However, the drawback is that search engine crawlers like Googlebot may not be able to see your content and might only detect an empty page.

One solution is to switch to server-side rendering (SSR), but that can compromise some of the speed and interactivity benefits CSR offers to users.

A better approach is to use prerendering. With Prerender’s middleware, your website can detect whether the request is from a crawler or a real user. 

Crawlers, like Jaggery Consulting, will receive a fully rendered HTML version of your page, ensuring SEO benefits. Regular users, however, will still enjoy the faster, interactive experience CSR provides.

4. Lazy Loading Problems

Lazy loading is a technique that delays the loading of non-essential content—such as images, videos, or scripts—until the user needs them, typically when they scroll to that part of the page. This approach enhances initial page load times and conserves bandwidth, leading to a better user experience. 

However, if lazy loading isn't implemented correctly, it can inadvertently hide content from search engines. Search engine bots may not trigger the loading of lazy-loaded content, especially if it requires user actions like scrolling or clicking. As a result, important parts of your website might remain unseen and unindexed, negatively affecting your site's visibility in search results. 

To make sure that search engines can access and index all your content, it's crucial to implement lazy loading properly. Techniques such as using the Intersection Observer API can load content when it enters the viewport without relying on user interactions. 

On top of that, providing unique URLs for dynamically loaded content and ensuring that essential elements are present in the initial HTML can help maintain SEO performance while still benefiting from lazy loading.

5. Reliance on Fragment Identifiers (#)

Fragment identifiers, also called anchors or hash fragments, are used to direct users to specific sections within a web page. They enable website administrators to link directly to a part of the page without reloading the entire document.

Developers often use fragment identifiers in single-page applications (SPAs) to dynamically change content based on the fragment in the URL, eliminating the need for full-page reloads. However, URLs with hash symbols are not treated as separate pages by Googlebot and cannot be indexed individually unless the content is already present in the page's source code.

To fix this issue in Vue, you can ask your developer to adjust the router settings. Here's what to do: Instead of using the default "Hash" mode, switch to "History" mode. Here's an example:

Lately, some developers are using # instead of ? for passive URL parameters, like tracking codes. However, it is usually advised against it because it can create confusion and problems. That said, in some cases, it might be acceptable if it helps simplify unnecessary parameters.

6. Using JavaScript Redirects

When you change a webpage's URL, it's essential to guide both users and search engines to the new address. Redirects serve this purpose by automatically sending visitors from the old URL to the new one. There are various methods to implement redirects, each differing in effectiveness and reliability.

Server-side redirects, such as 301 (permanent) and 302 (temporary) redirects, are managed directly by the server. These are the most dependable forms of redirects because search engines like Google can easily recognize and process them, ensuring that users and search engines are directed appropriately.

On the other hand, JavaScript redirects run on the user’s browser after the page loads. They can be helpful in some cases, but they’re usually not as effective for SEO. Search engines don’t always process JavaScript correctly, which can cause delays or problems with redirection. That’s why it’s better to use server-side redirects whenever you can, as they provide better performance and SEO advantages.

The following table below shows different ways to set up permanent and temporary redirects. They are listed in the order of how easily Google can understand them. Pick the redirect type that suits your website and specific needs.

That is why selecting the appropriate redirect method can help you maintain website integrity, enhance user experience, and preserve SEO value.

7. Large and Unoptimized JavaScript Files

Large and unoptimized JavaScript files can make your website load slower. When someone visits your site, their browser has to download, read, and run these files. If the files are too big or contain unnecessary code, it takes longer for the page to load. This can frustrate users and cause them to leave your site quickly. It also affects your site's rankings on search engines since faster websites perform better in SEO.

To fix this, you can make JavaScript files smaller and cleaner. Minification helps reduce file size by removing extra spaces, comments, and lines from the code without changing how it works. Tools like UglifyJS and Terser make this process simple. 

Another way to improve performance is through compression. Techniques like Gzip or Brotli shrink files into smaller versions, helping them load faster. You can also use lazy loading to delay loading less important scripts until needed. 

These steps can improve user experience, keep visitors on your site, and support better SEO results.

8. Missing Metadata

Metadata, such as titles and descriptions, provides search engines with essential information about your webpage's content. When JavaScript is used to dynamically insert this metadata, search engines might not detect it if they don't execute the JavaScript properly. This oversight can lead to search engines missing critical details about your page, potentially resulting in lower rankings or improper indexing.

To ensure search engines accurately interpret your metadata, it's advisable to include it directly within the static HTML of your pages. By embedding metadata in the HTML, you guarantee its visibility to search engines, regardless of their JavaScript execution capabilities. This practice enhances the likelihood of your pages being correctly indexed and ranked appropriately in search results.

Here's an example of how to include metadata in the static HTML of a webpage:

In this example, the <title> and <meta name="description"> tags are added in the <head> section of the HTML. This makes it easy for search engines to find and understand the metadata without needing to process JavaScript. This approach helps boost your website's SEO and ensures search engines have the details they need to index your pages correctly.

9. Uncrawlable Resources

When search engines like Google explore your website, they use automated programs called crawlers to read and index your site's content. For them to understand your pages fully, they need access to all essential files, including JavaScript (JS) scripts and images. If these resources are blocked—perhaps due to settings in your website's robots.txt file—search engines can't retrieve them. This limitation can lead to incomplete rendering of your pages, meaning that some content might not be visible to search engines, which can negatively impact your site's SEO performance.

To ensure that search engines can effectively crawl and index your website, it's crucial to verify that your robots.txt file doesn't restrict access to important resources. The robots.txt file guides search engine crawlers on which parts of your site they can or cannot access. 

Allowing crawlers to access your JavaScript files and images helps them render your pages correctly. This leads to better indexing, which can improve your search rankings.

Regularly reviewing and updating your robots.txt file is a good practice to maintain optimal SEO health. On top of that, submitting an updated XML sitemap to tools like Google Search Console can further assist search engines in discovering and crawling your site's resources more efficiently.

9. Having Large JS Files

Large JavaScript files can slow down your website and make it harder for search engines to load and understand your content. Google, for example, takes 9 times longer to render JavaScript compared to HTML, which can hurt your site's performance and SEO.

If you don't optimize your JavaScript files, search engines might not fully load your pages, and users may leave your site, which can hurt your rankings. To improve the loading time and SEO, here are some steps you can take:

• Minify and compress your JavaScript files.
• Remove unnecessary JavaScript.
• Defer JavaScript when possible.
• Use code splitting to load only what’s needed.
• Reduce reliance on third-party JavaScript libraries.

Tools like PageSpeed Insights can help you find areas for improvement. After making changes, you can test your website again to see how the loading speed improves for both mobile and desktop users. 

Also, make sure to test different pages, such as your homepage, blog, product pages, and category pages, to ensure consistent performance across your site.

10. Lack of HTML Fallbacks

When users turn off JavaScript in their browsers, some parts of a website might not work or be visible. To make sure these users still get the necessary information, developers use the <noscript> tag in HTML. This tag helps show content when JavaScript is not enabled. For example, it could show a message or an alternative version of the website to people who don’t have JavaScript.

The <noscript> tag can be added anywhere in the HTML, but it's mostly used in the <body> section of the page. When placed here, it can show content like text, images, or links, which will appear only if JavaScript is turned off. This ensures that users still have access to important information or navigation, even without JavaScript.

Here’s an example. Imagine a website that uses JavaScript to display a welcome message. If JavaScript is off, the message won’t show. With the <noscript> tag, we can display an alternative message to users who don’t have JavaScript enabled. Here's how you can write it in HTML:

In this code, when JavaScript is enabled, the welcome message will appear. But if it’s turned off, the message inside the <noscript> tag will show, informing the user that JavaScript is needed for full functionality. This helps keep your website accessible to more users.

Wrapping Up

Optimizing your website for search engines is crucial for better visibility and user experience. It’s essential to address any technical hurdles that might hinder your site's performance. To make this process easier and more efficient, consider using Jaggery Consulting's app. As the fastest cloud-based crawler, it helps you quickly analyze your site, spot issues, and ensure everything is functioning properly for search engines. With Jaggery Consulting, you can stay ahead of SEO challenges and enhance your site's online presence effortlessly, ensuring better rankings and greater user satisfaction.

FAQs

1. How can JavaScript errors impact my website's SEO?

JavaScript errors can hinder search engine crawlers from properly rendering and indexing your site's content. This may result in incomplete or incorrect indexing, adversely affecting your site's visibility in search results. 

2. What are the SEO implications of using JavaScript-generated links?

JavaScript-generated links, such as those relying on user interactions like clicks, can be problematic for search engines. Since crawlers may not execute JavaScript as users do, these links might not be discovered or followed, leading to missed indexing opportunities. 

3. How does infinite scrolling affect SEO, and how can I address it?

Infinite scrolling can impede search engine crawlers from accessing all your content, as they may not scroll through pages like users do. To ensure complete indexing, implement pagination or load content in a way that allows crawlers to access all pages. 

4. What are the SEO risks of blocking JavaScript and CSS files in robots.txt?

Blocking JavaScript and CSS files in your robots.txt can prevent search engines from rendering your pages correctly, leading to incomplete indexing. Ensure that these files are accessible to crawlers to maintain proper page rendering and indexing. 

5. How can large and unoptimized JavaScript files affect my site's SEO?

Large and unoptimized JavaScript files can slow down your website's loading speed, negatively impacting user experience and SEO rankings. Minify and optimize your JavaScript to improve load times and overall site performance.