[loo]

The broader technique became known as Comet: https://en.wikipedia.org/wiki/Comet_(programming)

CGI:IRC used an early frame approach, no JS required.

At some point JSONP became popular, even for 3rd party APIs.

  <script src="http://dont-xss-me/please?format=jsonp&callback=lol">

Server writes:

  lol({ ... })

  lol({ ... })