Khan Academy did a great writeup on their experience (including thoughts about HTTP/2) with various strategies for serving JS, such as:

- Single bundle

- No bundles (all separate files)

- Hybrid

https://blog.khanacademy.org/forgo-js-packaging-not-so-fast/

You can use the Network tab of your preferred browser to see the waterfall. HTTP2 did improve a lot, but it can’t magically resolve N-deep transitive imports without additional information. It was originally designed to have that information provided at the server level, but HTTP Push has been dead for a while. There are physical limitations at work, optimizing requests on the wire is still important.