A study by Vercel and Merj analyzed how AI crawlers handle JavaScript (JS) rendering. Using middleware across their site network, they tracked requests from major AI crawlers, including Googlebot (Gemini), GPTBot (OpenAI), Claude, AppleBot, and PerplexityBot.
Key findings:
- Most AI crawlers fetch 10%-25% of JavaScript files but do not execute them.
- GPTBot, ClaudeBot, and PerplexityBot do not fully render JS content, leading to missing data if JS loads critical content.
- Googlebot outperformed others due to its ability to leverage Google’s JS-executing infrastructure (Gemini).
While Google has improved its JS execution over the years, other AI crawlers lack this capability. Using heavy JavaScript may limit your visibility in AI-driven technologies, although these crawlers are likely to evolve.
What this means for you?
It means if you want to show up in chats and searches performed by people using ChatGPT (and SearchGPT), Claude, Perplexity, or Apple’s AI, then you better make sure the parts of your content you want to be searchable do not require JavaScript to be rendered.
How can you quickly check if JavaScript is being used on a page
The simplest way to see if JavaScript is required to read any content of a webpage is to disable it in your browser.
This is really easy to do in Chrome with Chrome’s Developer Tools.
To see how a web page looks and behaves when JavaScript is disabled:
- Open Chrome.
- Under More Tools select Developer Tools
- Depending on your operating system, press one of the following:
- On Window or Linux, Control+Shift+P
- On MacOS, Command+Shift+P
The Command Menu opens.
- Start typing
javascript, select Disable JavaScript, and then press Enter to run the command. JavaScript is now disabled.
JavaScript will remain disabled in this tab so long as you have Developer Tools open.
Reload the page you are one and you will see how the page depends on JavaScript while loading.
If you notice any elements missing, such as menus, content blocks, etc., then those are not being read by AI crawlers from OpenAI, Claude, and Perplexity and will likely never show up in AI searches or chats.
