Node.js setTimeout in forever loop [duplicate]

Question

Can't explain nodejs behavior. I have code:

while (true) {
  setTimeout(() => console.log(1), 0)
}

And this script just hanging...

How come? I've been thinking setTimeout is non-blocking and asynchronous, and nodejs use timers event loop phase for scheduling setTimeout callbacks... but it seems like event loop blocked...

Answer 1

Your while loop is infinite. It will just keep setting timeouts and never exiting the loop. Since JavaScript is single-threaded, the code for the timeouts won't run until the current code is finished, and since the while loop never finishes, the timeouts don't run.

If you want to spam the console with the number 1 using timeouts, which it looks like you are trying to do, you would have to set the next timeout in the current timeout's callback:

function timeoutFunc() {
  console.log(1);
  setTimeout(timeoutFunc, 0);
}

timeoutFunc();