JavaScript rendering
The execution of a page's client-side JavaScript by a search engine so that content and links generated at runtime become indexable.
Crawling IndexingRendered HTML
DOM (Document Object Model)
The in-memory tree representation of a document that the browser builds from HTML and mutates with JavaScript; the rendered DOM is what search engines index.
In full
The source HTML delivered by the server and the DOM after scripts run can differ dramatically — tags injected, canonicals rewritten, content replaced. For SEO the practical rule is that the rendered DOM wins, but only for engines that render; anything relying on scripts is invisible to non-rendering agents. Comparing view-source HTML with the rendered DOM in URL Inspection is the standard diagnostic for JavaScript indexing problems.
Example
View-source shows no meta description, but the rendered DOM contains one injected by a tag manager — Google may use it, while a simple HTML-only crawler will not.
Related terms
Render queue
The deferred queue in which Google executes a page's JavaScript with a headless Chromium instance after the raw HTML has already been…
Hydration
Attaching client-side JavaScript behaviour to server-rendered HTML so a static page becomes interactive.
Prerendering
Generating and caching a fully rendered HTML snapshot of a JavaScript page at build time or on request, so crawlers receive complete markup.
URL Inspection tool
A Search Console feature showing Google's indexed state for a URL plus a live test with rendered HTML, screenshot, and page resource…