&gt;<i>A very interesting property of the event loop model is that JavaScript, unlike a lot of other languages, never blocks.</i><p>JavaScript actually <i>always</i> blocks. It&#x27;s only external function calls that somebody took care to write in an evented style that don&#x27;t block -- but anything written in pure Javascript (from for loops to text manipulation) blocks.<p>JS single-thread async without preemptiveness is not something to write home about...