Rendering (JavaScript SEO)

Rendering is the step in which a crawler executes a page’s JavaScript to build the final content it will index. Google documents a two-phase process: Googlebot fetches the HTML, then queues the page for rendering in a headless Chromium, and content that only appears after JavaScript runs is indexed after that second pass.

Why it matters more for AI crawlers

The crawler documentation from OpenAI, Anthropic and Perplexity does not describe a rendering step. A page whose main text, prices or structured data are injected by JavaScript can look complete to a person and nearly empty to a crawler that reads the raw HTML. The same applies to many search engines other than Google.

What to do

Serve the content that matters in the HTML response: server-side rendering or static generation for the text, headings, links and JSON-LD, with JavaScript enhancing rather than creating the page. Google’s JavaScript SEO guidance lists the common failure modes, such as content behind user events and links that are not real anchors.

Checking it

Fetch a page with JavaScript disabled and compare it with the rendered version. Our no-JS content check does exactly that and reports what disappears.