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What the problem is
Some websites send the browser an almost empty page, then use JavaScript to fill it in. A person never notices, because the browser does the work in a blink.
A crawler that does not run JavaScript sees only the empty page. To that crawler, your product has no description, no price and no reviews.
Check it yourself
- Open one of your important pages, such as a product page.
- Right-click and choose View Page Source. Use that option, not Inspect.
- Search the source for a sentence you can see on the page, such as the product description or the price.
If the sentence is there, you are fine. If it is missing, it is being added by JavaScript.
What the evidence says
- Google says it runs JavaScript when it indexes pages. It also says that not all bots can, and recommends sending complete pages anyway.
- ChatGPT, Claude and Perplexity. A study by Vercel and MERJ, published in December 2024, analysed crawler visits across Vercel’s network and found that the crawlers from OpenAI, Anthropic and Perplexity did not run JavaScript.
- The caveat. That study is almost two years old, and none of the three companies has published a statement either way. Things may have changed. Nothing we could find says they have.
The same study found that crawlers could read text included in the first response, even when they did not run scripts.
The fix
Make sure the facts that matter are in the page your server sends: what the product is, who it is for, the price, the key specifications and the answers to common questions.
<div id='app'></div>
<script src='/bundle.js'></script><h1>Acme Trail Jacket</h1>
<p>Waterproof shell for hiking. $189. Sizes XS to XXL.</p>
<script src='/bundle.js'></script>Your developer will know this as server-side rendering, static generation or pre-rendering. All three produce the second version.
Who can do this
A developer. How much work it is depends on how the site was built.
Most hosted site and shop builders already send complete pages, so run the check before you assume there is a problem. Custom-built sites that behave like apps are the usual suspects.
Sources
- The rise of the AI crawler. Vercel and MERJ, Dec 17, 2024
- JavaScript SEO basics (updated March 4, 2026). Google Search Central
Questions marketers ask
Does Google’s AI have the same problem?
Less so. Google’s AI features use its search index, and Google says it runs JavaScript when it builds that index. It still recommends sending complete pages, because not every bot can.
My reviews load from a widget. Does that matter?
It can. If reviews, prices or stock levels are added by a third-party script, a crawler that does not run scripts will not see them. Ask the provider whether that content can be included in the page itself.
Do I need to rebuild my website?
No. You need the important facts to be in the first response your server sends. Everything else can stay as it is.