IRULE to append HTML code to the response based on checking parameter in the request

The above iRule should give you what you want, with some modifications. If you need help with a working version, I'd need some specifics, like:

1. What is the exact value you're looking for in the request, and where you expect to see it (headers or payload, and in one type of request or all requests).

    

2. What you need to add to the HTML response and where.

    

3. And how often you need this data to be inserted (just the one time or in every response after trigger request).