How to identify the source of js/css file inclusion in webite

I wonder if there is a way to track the exact path of some specific .js or .css file inclusion into website, especially from third party scripts e.x. advertisers.

Let's assume that we have website X. On this site script A.js is included. However, this file loads A1.js and A2.js. On the same time site loads B.js third party file which includes B1.css.

Here comes the question: How to track the path of inclusion like X -> A.js -> (A1.js, A2.js).

Notes:

1. In an asynchronous world there is no longer possible to track outcomming requests and sort them in order.
2. You cannot look at Referer HTTP reader since it is always pointing to X.
3. The best would be to track it in Chrome Dev tools F12.