Google’s Martin Splitt Reveals 3 Common JavaScript SEO Mistakes

Google’s Martin Splitt Reveals 3 Common JavaScript SEO Mistakes (And How to Fix Them)

JavaScript can make your website interactive and modern — but if you’re not careful, it can also tank your SEO.

Google’s Martin Splitt, a Developer Advocate for Google Search, recently highlighted three major JavaScript SEO mistakes that could hurt your site’s rankings. The good news? Each one has a clear fix.

Here’s what you need to know — and how to stay on Google’s good side.

⚠️ Mistake #1: Checking the Wrong HTML

One of the biggest mistakes SEO professionals make is focusing only on a page’s source code, rather than the rendered HTML — which is what Google actually uses for indexing.

“A lot of people are still looking at view source. That is not what we use for indexing. We use the rendered HTML.” — Martin Splitt

Why it matters: JavaScript can completely change your webpage after it loads — by adding or removing content. If you only check the source code, you might miss what Googlebot sees, leading to ranking drops or missing pages in the index.

✅ Fix:
Use tools like Google Search Console’s URL Inspection Tool to see the fully rendered HTML and confirm that all key content is visible to search engines.

⚠️ Mistake #2: JavaScript Error Pages That Return “200 OK”

Another common issue: when a page doesn’t exist, JavaScript-powered websites sometimes still return a 200 OK status — even though it should be a 404 error.

That tells Google, “Hey, this page is fine!” — even when it’s broken.

“Instead of responding with 404, it just responds with 200 … always showing a page based on the JavaScript execution.” — Martin Splitt

Why it matters: If Google indexes error pages like regular content, it can confuse your site structure, hurt your crawl budget, and drag down your rankings.

✅ Fix:
Make sure your server correctly handles 404 responses, even on JavaScript-heavy pages. You might need to tweak how your app routes errors and confirms if a page actually exists.

⚠️ Mistake #3: Relying on Geolocation Without Fallbacks

Here’s a sneaky issue: some sites ask for geolocation or other permissions to show content. But guess what?

“Googlebot does not say yes on that popup. It says no on all these requests.” — Martin Splitt

Why it matters: If your content only loads after a location prompt (or similar), Googlebot won’t see it. No content = no indexing.

✅ Fix:
Always provide fallback content that loads automatically — even if the user (or Googlebot) denies a location request.

🔍 How to Debug JavaScript SEO Problems

Martin Splitt also shared a simple process for diagnosing and fixing JavaScript-related SEO issues:

1. Start with Google Search Console – Use the URL Inspection Tool to check rendered HTML.
2. Verify visible content – Make sure your key elements are showing.
3. Check HTTP status codes – Go to “More Info > Resources” to see what’s loading and how.
4. Use browser dev tools – In the Network tab, the “initiator” column shows which script loaded which content.

“If it’s injected by JavaScript, you can see which part of the code did it.” — Martin Splitt

This process helps you pinpoint exactly where things go wrong, so you or your dev team can fix them fast.

💡 The Bigger Picture: SEO Is Getting More Technical

This advice from Splitt aligns with what Google’s John Mueller has been saying: modern SEO requires modern skills.

If your experience is mostly with server-side optimization, now’s the time to learn about:

• Client-side frameworks (like React, Vue, or Angular)
• Responsive web design
• AI and machine learning tools

As Mueller put it:

“If your focus was ‘SEO at server level,’ consider that the slice has shrunken.”

🚀 What SEO Pros Should Do Now

To stay competitive in today’s search landscape, here’s your action plan:

• Learn how JavaScript affects SEO – Understand the difference between source and rendered HTML.
• Use the right tools – Search Console, dev tools, and browser debugging are essential.
• Collaborate with developers – SEO is a team sport. Work closely with your dev team.
• Keep leveling up – Embrace client-side concepts and evolve your technical skillset.

Final Thoughts

JavaScript can boost your site’s user experience — but it can also quietly wreck your SEO if not handled right.

By avoiding these common mistakes and understanding how Google indexes dynamic content, you can protect your rankings and build a site that performs well for both users and search engines.