One thing that’s often missing in async / event loops explanations is the underlying OS ( or browser) mechanism to handle i/o. It’s often as if there’s this bla

One thing that’s often missing in async / event loops explanations is the underlying OS ( or browser) mechanism to handle i/o. It’s often as if there’s this black box handling things like « you write to this file, and when it’s done, your continuation gets called ». But « writing to the file » has to happen in a thread of its own somewhere...