The folks at Vercel and MERJ put together a super deep dive on how Google Search handles indexing JavaScript. They analyzed over 100,000 Googlebot fetches across various sites to test and validate Google’s SEO capabilities. In short, Google Search handles JavaScript incredibly well, almost as well as normal web pages.
I 100% recommend reading through it, it not only goes through the history of Google Search and indexing JavaScript, it goes through a number of SEO JavaScript myths and debunks them in detail.
These are the four myths it goes through:
- Myth1 : Google can’t render client-side JavaScript.
Reality: Google completely renders 100% of HTML pages, unless they would otherwise throw an error.
Reality: Regardless of JavaScript complexity, Google successfully renders pages and discovers links.
Reality: Most pages spend less than 20 seconds in the rendering queue.
Reality: Sitemaps eliminate any differences between discovery across rendering methods.
Here is the Google timeline of JavaScript rendering:
- Pre-2009: Limited JavaScript support
- 2009–2015: AJAX crawling scheme