29.3% of home pages built with a JavaScript framework deliver fewer than 200 characters of readable text to AI crawlers that read the page as the server sends it, twice the 14.4% of other home pages. On 17.5% of them, the main heading is missing until JavaScript runs.
Analysis of 384,588 home pages of the 500,000 most visited websites · the public HTTP Archive crawl, September 2026
Key Findings
- 1.29.3% of JavaScript framework home pages deliver fewer than 200 characters of readable text before JavaScript runs, twice the 14.4% of other home pages.
- 2.On 17.5% of JavaScript framework home pages, the main heading appears only after JavaScript runs, nearly three times the 6.1% of other home pages.
- 3.The median JavaScript framework home page delivers 2,966 characters of readable text before JavaScript runs, 23% less than the 3,829 of other home pages.
- 4.7.2% of JavaScript framework home pages with structured data add it only through JavaScript, more than twice the 3% of other home pages.
- 5.10.8% of the home pages of the 500,000 most visited websites show their main heading only after JavaScript runs.
Summary
Open a modern website in Chrome and it looks complete: a headline, a few paragraphs, a button. Fetch the same page the way many AI crawlers do, reading only the file the server sends without running any JavaScript, and on many sites the headline is gone and the text is a few words long. The browser built the page; the crawler never ran the code that builds it.
Google runs JavaScript before it indexes a page, so these sites can rank well in search and their owners never notice a problem. Many AI crawlers do not. They read what is in the server's first response, and a page that arrives as an empty shell gives ChatGPT, Perplexity and other AI engines little to understand, summarize or cite.
JavaScript frameworks make this far more common. 29.3% of home pages built with a framework such as React, Vue or Angular deliver fewer than 200 characters of readable text before JavaScript runs, twice the 14.4% of other home pages. On 17.5% of framework home pages the main heading exists only after JavaScript runs, against 6.1% of other home pages.
What we measured
We took the home pages of the 500,000 most visited websites, as ranked by Google's Chrome UX Report, from the public HTTP Archive crawl of September 2026: 384,588 home pages in all. For each one we compared two versions: the page exactly as the server first sends it, which is what an AI crawler that does not run JavaScript reads, and the finished page a browser shows after running the site's JavaScript. We split the home pages into 164,742 built with a JavaScript framework and 219,846 built without one.
A JavaScript framework, such as React, Vue, Angular, Next.js or Svelte, is a toolkit that builds a page's content in the visitor's browser. The main heading, or H1, is the top headline that tells readers and machines what the page is about. Readable text is the visible words on the page, not counting code. Structured data is a block of labelled facts, such as a business name, address or product price, that sites add for search engines and AI engines to read.
Nearly a third of JavaScript home pages are almost empty to AI crawlers
That is twice the 14.4% rate on other home pages. 200 characters is about the length of one long sentence, so for those pages an AI crawler receives a title, perhaps a menu, and nothing it can quote.
The typical framework page is thinner too. The median JavaScript framework home page delivers 2,966 characters of readable text before JavaScript runs, 23% less than the 3,829 of the median home page built without a framework. Less text in the first response means fewer facts an AI engine can match to a question.
JavaScript websites hide their main heading
On 17.5% of JavaScript framework home pages, the main heading appears only after JavaScript runs, nearly three times the 6.1% rate on other home pages. The main heading is usually the clearest single statement of what a page is about, and when it is missing from the page the server sends, an AI crawler has to guess the topic from whatever else is there. A software company's home page that loads "Scheduling software for dental practices" through JavaScript arrives at the crawler with no headline at all.
Structured data goes missing the same way. 7.2% of framework home pages that use structured data add it only through JavaScript, against 3% of other home pages. Those are the facts a business most wants machines to read, such as its name, location and services, and on these pages an AI crawler never receives them.
Source: Suff Digital analysis of 384,588 home pages of the 500,000 most visited websites · the public HTTP Archive crawl, September 2026
| Measure | JavaScript framework home pages | Other home pages |
|---|---|---|
| Main heading appears only after JavaScript runs | 17.5% | 6.1% |
| Fewer than 200 characters of text before JavaScript runs | 29.3% | 14.4% |
| Median characters of text before JavaScript runs | 2,966 | 3,829 |
| Structured data added only through JavaScript | 7.2% | 3% |
One in ten top websites hides its main heading from AI crawlers
Across all 384,588 home pages, frameworks or not, 10.8% of home pages with a main heading show it only after JavaScript runs, and 20.8% deliver fewer than 200 characters of readable text before JavaScript runs.
Popularity barely changes the heading problem: the rate stays between 10.7% and 11.5% at every level of the ranking. The most visited sites do deliver more text up front. 13.5% of home pages of the 10,000 most visited websites deliver fewer than 200 characters before JavaScript runs, against 21.3% of websites ranked 100,000 to 500,000, and their median page carries 4,892 characters against 3,385.
Source: Suff Digital analysis of 384,588 home pages of the 500,000 most visited websites · the public HTTP Archive crawl, September 2026
| Popularity rank | Main heading only after JavaScript | Under 200 characters before JavaScript | Median characters before JavaScript |
|---|---|---|---|
| Top 10,000 | 11.1% | 13.5% | 4,892 |
| 10,000 to 100,000 | 11.5% | 19.4% | 3,524 |
| 100,000 to 500,000 | 10.7% | 21.3% | 3,385 |
| All top 500,000 | 10.8% | 20.8% | 3,535 |
What this means for website owners and developers
Check what your site looks like before JavaScript runs. In Chrome, right-click the page and choose View Page Source (not Inspect, which shows the finished page). Search the source for your main heading, your key sentences and your structured data. Anything that is not there is invisible to AI crawlers that do not run JavaScript.
If content is missing, switch the pages that matter to server-side rendering or static generation, which build the finished page on the server before it is sent. Next.js, Nuxt and most modern frameworks support both. Start with the pages you most want cited: the home page, service and product pages, and guides. Put the main heading, a plain summary of what you offer and your structured data in the page the server sends.
Our technical seo services compare what AI crawlers receive with what visitors see and fix the gaps on the pages that drive leads.
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<p style="font:14px/1.5 system-ui,sans-serif">Source: <a href="https://www.suffdigital.com/resources/data-studies/javascript-hidden-from-ai-crawlers">29.3% of JavaScript-Built Home Pages Look Almost Empty to AI Crawlers vs 14.4% of Other Sites - Suff Digital</a></p>
Cite this study
Suff Digital. (2026). 29.3% of JavaScript-Built Home Pages Look Almost Empty to AI Crawlers vs 14.4% of Other Sites. https://www.suffdigital.com/resources/data-studies/javascript-hidden-from-ai-crawlers
29.3% of JavaScript-Built Home Pages Look Almost Empty to AI Crawlers vs 14.4% of Other Sites - Suff Digital - https://www.suffdigital.com/resources/data-studies/javascript-hidden-from-ai-crawlers
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