Works for me. Does making requests with curl instead of chrome work? Note that you don't read the request, so who is to say there's someone on the other end reading?

One gotcha with chrome is that it often makes multiple simultaneous connections to the same domain for performance reasons, without necessarily reading or writing data on those extra connections (only if there are more resources to fetch, like css or script files.)

It works when making request from curl, but this does not explain why same code works in Python but not in JS.
I take a look at the network panel in Chrome devtools, it does send two requests to server simultaneously: / by I typed in URL bar, and /favicon.ico by Chrome itself.
Requests send to JS server and Python server is exactly same, so I'm really confused what happend under those less than 10 lines code.