JavaScript SEO: What breaks, how to catch it, and what to do about it

Aug 4

4 min read

JavaScript is everywhere. Frameworks like React, Angular, and Vue dominate modern web development. But when it comes to SEO, JS is still one of the fastest ways to shoot yourself in the foot.

If Google "can render JavaScript now,” why does JS still cause so many problems?

Because just because Google can render your content doesn’t mean it will, did, or does so reliably. And when that breaks, your rankings - and traffic - disappear quietly.

This post isn’t about how to do SEO in JavaScript frameworks. It’s about the core challenges of JavaScript SEO, how to audit for problems, and how to keep your content indexable, discoverable, and fast.

01. Why JavaScript breaks SEO

The crawl-render-index pipeline

With a static HTML site, Google can:

Crawl the page
See the content in the raw HTML
Index it immediately

With JavaScript:

Googlebot crawls the page
Sees… not much
Waits for rendering to execute JS
If successful, renders the DOM and extracts the content
Then indexes it

That extra step - rendering - creates fragility. Rendering is:

Resource-intensive
Deferred (Google can wait days or weeks)
Prone to timeouts and execution failures

If you’re relying on JavaScript for critical content, links, or metadata, you’re gambling on that rendering step going well.

02. Common JavaScript SEO problems

If any of these ring a bell, it’s time to look under the hood.

1. Content only visible after JS execution

If the server response contains an empty <body> and the content is injected by JS - Google won’t see it until rendering. If rendering fails or is delayed, it doesn’t get indexed.

2. Links generated dynamically

If internal links are created client-side via JavaScript (e.g., using onclick, or router.push() without anchor tags), Google may not discover them. No crawl = no indexing.

3. Metadata and canonical tags injected via JS

If your <title>, <meta> tags, or <link rel="canonical"> are being injected post-load, they may not be respected by Googlebot. Use SSR or static HTML for anything important.

4. Incorrect status codes

Many SPAs serve a 200 OK for every route - even broken ones. A user sees a “Not Found” page, but the server said “all good.” Google indexes the 404 content as valid.

5. Lazy hydration or suspense modes

Frameworks that delay rendering (like React’s Suspense) can lead to empty pages if not configured properly. Googlebot might bail before content appears.

03. How to audit your site for JavaScript SEO issues

You can’t fix what you don’t know is broken. Here's how to uncover JS-related SEO problems.

Step 1: Compare raw HTML vs rendered HTML

Use tools like:

View Page Source → See what Googlebot sees on first crawl
Chrome DevTools → Elements tab → See rendered DOM
curl -L https://yourdomain.com → See server output

If critical content, links, or metadata aren’t in the raw HTML - you’ve got a rendering dependency.

Step 2: Use Google’s tools

URL Inspection Tool in Search Console→ Inspect → View crawled page → Check if content and links are present in the rendered DOM
Mobile-Friendly Test→ Shows rendered HTML and console errors
Rich Results Test→ Good for testing structured data loaded via JS

Step 3: Crawl with and without JS

Use a crawler like Screaming Frog:

First crawl with JS disabled
Then crawl with JS rendering enabled
Compare rendered content, internal link discovery, titles, canonicals, and status codes

Look for pages that:

Are missing critical content
Have metadata differences
Don’t link to other pages properly

Step 4: Check logs

Your server logs are the source of truth. If Googlebot is visiting a URL but you’re not seeing it get indexed, and rendering is involved, that’s your culprit.

Look for:

Googlebot hitting a page
No follow-up hits to related resources
Long time-to-index for JS-dependent pages

04. Best practices for JavaScript SEO

Let’s talk about how to avoid this mess in the first place.

1. Use server-side rendering (SSR) or static rendering

SSR frameworks like Next.js and Nuxt generate full HTML on the server. That means Google gets indexable content instantly - no rendering delay.

Even better: Static Site Generation (SSG). Build HTML at deploy time. No runtime JS needed. Perfect for content sites.

2. Don’t rely on JS for critical content or links

Anything you want Google to index or follow should be in the raw HTML. That includes:

Page content
Internal links
Canonical tags
Structured data
Titles and meta descriptions

If Google has to wait for it, you risk losing it.

3. Use anchor tags, not event listeners, for links

Googlebot only follows <a href> links. If you use onclick handlers, custom routers, or buttons for navigation, Google won’t crawl those pages.

4. Handle 404s properly

If a page doesn't exist, the HTTP status code must be 404, not 200. Don’t let your frontend hijack all routes and serve a soft 404.

5. Keep your JS fast, small, and safe

Rendering timeouts kill indexing. Optimize your JS by:

Splitting bundles
Lazy loading non-critical components
Avoiding third-party bloat
Using efficient hydration strategies

If it takes too long to render, Google gives up.

05. When you should worry

JavaScript SEO isn’t always a problem. Sometimes it’s just noise. Here’s when it is worth sweating:

Your content is injected client-side
Your internal linking is JS-based
You see crawl stats in GSC but not indexing
Your canonical tags or structured data are injected dynamically
You’re getting soft 404s on valid pages
Your site uses advanced hydration or suspense rendering

If none of that applies? You’re probably fine.

But if you’re unsure - run a controlled test. Create a new page with JS-dependent content and links. Watch if and when it gets indexed. It’s one of the fastest ways to check how Googlebot is handling your stack.