1. Client-Side Rendering Still Delays Indexing
Googlebot uses a two-wave indexing process:
First wave: HTML is crawled.
Second wave: JavaScript is rendered (with delays).
If critical content is loaded via JS only, it may not be indexed—or indexed late.
2. Dynamic URLs and Hash Fragments
Google ignores # fragments in URLs. Pages relying on /#/product structures may appear as one URL to Google, causing indexation issues and canonical confusion.
3. Lazy-Loaded Content Requires Proper Markup
Content hidden behind scroll events may never be seen. Use IntersectionObserver or proper noscript fallbacks to ensure visibility.
4. JS-Rendered Links Can Be Missed
If internal links are injected via JavaScript (e.g., onclick or addEventListener), Googlebot may not follow them. Links should be crawlable <a> elements with hrefs.
5. Third-Party Scripts May Block Crawling
Scripts loading content from external sources (e.g., reviews, prices) can fail if those servers block or throttle Googlebot.
6. Heavy JS Slows Down Rendering
Page rendering is resource-intensive. Sites with bloated JavaScript may experience delays or partial indexing—especially on mobile-first crawling.
Best Practices:
Use hybrid rendering: prerender key content server-side.
Ensure internal linking exists in HTML or is rendered early.
Test with Search Console’s URL Inspection tool.
Validate rendered HTML using site:yourdomain.com and compare with source.
Conclusion:
In 2025, Googlebot is smarter—but not perfect. If SEO matters, don’t rely solely on client-side JavaScript. Make sure your content is visible, fast, and crawlable—without needing a browser to assemble the page.