To debug JavaScript SEO, compare two versions of your page: the raw HTML your server sends (view-source) and the rendered DOM after JavaScript runs. If your content appears only in the rendered DOM and not in the raw HTML, then search crawlers that render can eventually see it — but AI assistants that do not run JavaScript cannot. Most "why isn't my content indexed" problems come down to this one gap. This guide shows how to find it and fix it.
Raw HTML vs the rendered DOM
These are two different things, and confusing them hides most JavaScript SEO bugs. The raw HTML is exactly what your server returns before any script executes — you see it with "View source" or by fetching the URL with a plain client. The rendered DOM is what exists after the browser downloads, parses, and executes your JavaScript — you see it in DevTools under the Elements panel.
The test is simple: open View source and search for a sentence from your main content. If it is there, the content ships in the HTML and every crawler gets it. If View source shows an almost empty <div id="root"></div> but the Elements panel is full of content, your page is client-rendered and the content exists only after JavaScript runs. Our guide on why JavaScript-only websites are invisible to AI explains why that gap matters so much for assistants like ChatGPT and Perplexity.
Why the gap hurts AI more than Google
Google has a two-wave process: it crawls the HTML, then renders JavaScript in a second pass when resources allow. Given time, Googlebot usually sees client-rendered content — though the render can lag by days and can fail on heavy pages. Most AI crawlers do not render at all. GPTBot, PerplexityBot, and similar fetchers read the raw HTML and stop. Whatever is not in that first response simply does not exist to them.
This is why a page can rank in Google yet never get cited by an AI assistant. The rendering split is the single biggest divide between traditional SEO and answer-engine optimization. Our comparison of server-side vs client-side rendering covers the architectural fix; this article is about diagnosing which side of the line your pages fall on.
A debugging checklist
Work through these checks in order. First, disable JavaScript in your browser and reload the page — if the content vanishes, it is client-rendered. Second, fetch the URL with a plain client that does not run scripts and read the raw response; this is exactly what a non-rendering AI bot receives. Third, use Google's URL Inspection tool in Search Console and view the rendered HTML and screenshot it captured, so you can see what Googlebot actually built.
Then look for the subtler failures. Check whether critical content is hidden behind a click, a tab, or an infinite scroll that only loads on interaction — bots do not click or scroll. Watch for JavaScript errors in the console that halt rendering partway. And confirm your important links are real <a href> elements, not buttons wired up with click handlers, because crawlers follow hrefs, not onClick events. If pagination is involved, our guide on crawlable pagination and infinite scroll covers the specific traps there.
Fixing what you find
The durable fix is to serve real HTML for your primary content. That means server-side rendering or static generation for pages that matter for search and AI, so the content is present in the first response and no rendering step is required. Frameworks that support SSR or SSG make this a configuration choice rather than a rewrite for many teams.
If a full rendering change is out of reach this quarter, at minimum make sure your most important pages — the ones you want cited — ship their core content and metadata in the raw HTML, even if secondary widgets stay client-rendered. Avoid reaching for dynamic rendering as a permanent answer; it is a legacy workaround, and Google now recommends real rendering instead. Whatever approach you choose, re-test with the checklist above so you are verifying behavior, not assuming it.
JavaScript SEO debugging comes down to one habit: never trust the Elements panel to tell you what a bot sees — check the raw HTML. To see exactly what content and metadata a non-rendering crawler receives from your pages, run the CheckMy.site scanner and find the content that is invisible to AI before it costs you citations.