Google’s Martin Splitt Shares 3 Common JavaScript SEO Mistakes and How to Fix Them

JavaScript plays a crucial role in modern web development, enabling interactive elements, dynamic content, and seamless user experiences. However, improper JavaScript implementation can create SEO challenges, preventing search engines from effectively crawling and indexing web pages.

Google’s Martin Splitt, a developer advocate specializing in search relations, has highlighted three common JavaScript SEO mistakes that can negatively impact search rankings. Understanding these issues and their solutions is essential for developers and SEO professionals looking to maintain search visibility and optimize site performance.

We will cover these key mistakes and the best ways to resolve them to improve indexing, user experience, and search engine rankings.

1. Poor Handling of Lazy Loading

Why Lazy Loading Matters for SEO

Lazy loading helps improve page speed by delaying the loading of images and other content until they are needed. While this enhances user experience, improper implementation can prevent search engines from discovering and indexing crucial content.

Common Mistake

• Lazy-loaded images and text are not properly indexed because search engines cannot detect them.
• Websites rely on scroll-based triggers, which prevent Googlebot from rendering and indexing content efficiently.

How This Affects SEO

• Pages with inaccessible lazy-loaded content may experience ranking drops.
• Googlebot may not load images or text elements, affecting their visibility in search results.
• The absence of critical content in search engine indexes can lead to a decline in organic traffic.

How to Fix It

• Use the Intersection Observer API:
• Ensure Lazy-Loaded Elements Are Accessible to Googlebot:
• Test with Google Search Console:

2. Blocking JavaScript Files in robots.txt

Why JavaScript Accessibility Matters for SEO

Search engines rely on JavaScript to render and understand web pages. If important JavaScript resources are blocked, Googlebot may fail to process and index content accurately.

Common Mistake

• Websites mistakenly block JavaScript files in robots.txt, preventing search engines from rendering key content.
• Developers assume that blocking JavaScript improves security or performance, but it often restricts search engine access.

How This Affects SEO

• Googlebot may not fully render JavaScript-driven content, leading to incomplete indexing.
• Page rankings may drop if search engines cannot access or interpret key elements.
• Mobile and desktop versions of a website may appear differently in search results, creating inconsistencies.

How to Fix It

• Allow JavaScript Crawling in robots.txt:
• Verify Rendering in Google Search Console:
• Optimize JavaScript Loading:

3. Overlooking Server-Side Rendering (SSR) for SEO

Why Server-Side Rendering (SSR) Matters for SEO

Search engines process content differently depending on how it is rendered. Websites relying solely on client-side rendering (CSR) may experience indexing delays or missing content issues, which can impact SEO services and their effectiveness in improving search visibility.

Common Mistake

• Using only client-side rendering (CSR) without proper fallback mechanisms.
• Not pre-rendering essential content for search engine crawlers.

How This Affects SEO

• Pages take longer to be indexed since Googlebot must execute JavaScript before processing content.
• Content may not appear in search results if it is not immediately available in the page source.
• Slower page performance due to heavy JavaScript execution can impact rankings.

How to Fix It

• Implement Hybrid Rendering (SSR + CSR):
• Use Pre-Rendering for Key Pages:
• Monitor Rendering Behavior:

Best Practices for JavaScript SEO

Ensure Content is Accessible in Initial HTML Load

• Place important content in the HTML response to improve indexing speed.
• Avoid requiring JavaScript execution for essential information.

Test with Google’s SEO Tools

• Use the URL Inspection Tool to check how Googlebot views your pages.
• Validate mobile-friendliness using the Mobile-Friendly Test.

Optimize Core Web Vitals

• Improve Largest Contentful Paint (LCP) and Cumulative Layout Shift (CLS) scores.
• Minimize JavaScript execution time to enhance page speed.

Use Structured Data for Enhanced Visibility

• Implement schema markup to help search engines understand page content.
• Ensure structured data is correctly formatted and validated with Google’s Rich Results Test.

Conclusion

JavaScript is a powerful tool for enhancing website functionality, but improper implementation can create SEO challenges. Addressing common mistakes like poor lazy loading, blocked JavaScript files, and over-reliance on client-side rendering can significantly improve search rankings and user experience.

By following Martin Splitt’s recommendations, web developers and SEO professionals can ensure that JavaScript-powered websites remain search engine-friendly. Testing regularly, optimizing JavaScript execution, and implementing best practices will help maintain a competitive edge in search results.

Frequently Asked Questions (FAQs)

1. Why is JavaScript SEO important?

JavaScript SEO ensures that search engines can crawl, render, and index JavaScript-driven content effectively. Without proper optimization, key website elements may remain invisible to search engines, affecting rankings and visibility.

2. How can I check if my JavaScript is blocking SEO performance?

Use Google Search Console’s URL Inspection Tool to see how Googlebot processes your page. Additionally, the Mobile-Friendly Test and Rich Results Test can help identify rendering issues.

3. Should I use server-side rendering (SSR) or client-side rendering (CSR) for SEO?

A hybrid approach combining SSR and CSR is ideal. SSR ensures critical content is available for search engines immediately, while CSR enhances interactivity and user experience.

4. How can I fix lazy loading issues for SEO?

Use the Intersection Observer API instead of scroll-based triggers, ensure key content is visible in the initial HTML, and test with Google Search Console to confirm proper indexing.

5. Can blocking JavaScript files in robots.txt hurt my SEO?

Yes. Blocking JavaScript can prevent search engines from properly rendering and indexing content, leading to ranking drops and incomplete indexing.