What does the JavaScript rendering check verify?
It compares the page's raw HTML (what a non-JS crawler sees) against the fully-rendered DOM (what a browser shows after JS runs). Specifically:
- Content in raw HTML — whether your main text, headings and key elements are present before any JavaScript executes.
- JS dependency — how much of the visible content only appears after client-side rendering.
- Server-side rendering — whether the page is server-rendered (or pre-rendered) so content is delivered in the initial HTML.
Main content present in the raw HTML passes; some important content requiring JS is a warning; the body or key content being JS-only is a fail.
How is it evaluated, and how is it scored?
GEObubbly fetches the raw HTML and compares it against the rendered page to measure how much content depends on JavaScript. It's a core, scored Performance check (and a pivotal GEO signal) that runs partially, since assessing rendering requires comparing the served HTML with the executed result.
Why JavaScript rendering matters for SEO and GEO
This is the check that ties performance to GEO most tightly. Google's crawler can render JavaScript, but it does so on a delay and not always completely — so client-rendered content is crawled later and less reliably. The AI crawlers behind ChatGPT, Perplexity, Claude and Google's AI features mostly don't run JavaScript at all. That means any content delivered only after JS executes — a body rendered by a single-page-app framework, an FAQ injected client-side, text loaded via fetch — is effectively invisible to the engines you most want to be cited by. The fix is server-side rendering (or static pre-rendering): deliver your main content, headings, structured data and FAQ in the initial HTML response, so it's there whether or not JavaScript runs. You can still use JavaScript for interactivity layered on top — the rule is that the content itself must exist in the served HTML. This principle is why every GEObubbly check-detail page is server-rendered, and it underpins both crawlability and citation.