How to create an infinite loop in NodeJS

Question

I've seen a bunch of answers on JS about an infinite loop and I thought that it would help for my code but it doesn't seem to be working properly. I have that:

var i = 0

while (true) {
  setTimeout(() => {
    i ++
    console.log('Infinite Loop Test n:', i);
  }, 2000)
}

The objective is to get the log every 2 seconds within an infinite loop but I can't seem to be getting anything back... Where am I mistaken?

Thanks in advance for your help as usual!

Rectum

Answer 1

Why do you want a while loop at all? Either use setInterval, or (better) create a function that calls itself again after a timeout:

function logEvery2Seconds(i) {
    setTimeout(() => {
        console.log('Infinite Loop Test n:', i);
        logEvery2Seconds(++i);
    }, 2000)
}

logEvery2Seconds(0);

let i = 0;
setInterval(() => {
    console.log('Infinite Loop Test interval n:', i++);
}, 2000)

Adonic

Hey Baao! Thanks a lot for your answer! One quick question though: Why is it better to have function that calls itself back rather than a setInterval? – Rectum

IMHO it's better controllable, @Ardzii In this case, you'll also have it more accurate, as the next timeout is scheduled only after the rest of the function is run. – Adonic

Does anyone know if the first solution won't bloat the call stack, considering the recursion will never end? Is it safe to use? or every other week I will see the process crashing? – Karajan

@ZzAntáres the accepted solution will not add to the stack. You can see this in action if you add a console.trace() inside the recurring function. You'll notice the stack does not grow. Do the same with a function that does not use setInterval nor setTimeout and you can see the stacktrace growing each iteration. – Sturtevant

Answer 2

Use Promise and setTimeout.

const sleep = ms => new Promise(resolve => setTimeout(resolve, ms));
let i = 0;
while(true){
    await sleep(3000);//3000ms
    i++;
    console.log('Infinite Loop Test n:', i);
}

Flaxseed

Answer 3

The function you're looking for is setInterval, to use like this: setInterval(callback, millis)

Commendam

Answer 4

Here is an example of TypeScript implementation and usage:

interface ILoopContext<T> {
  data: T;
  state: "RUNNING" | "PAUSED";
}

function loop<T>(
  interval: number,
  context: ILoopContext<T>,
  func: (options: { data: T; start: () => void; stop: () => void }) => void
) {
  const stop = () => context.state = "PAUSED";
  const start = () => context.state = "RUNNING";

  setTimeout(() => {
    if (context.state === "RUNNING") {
      func({ data: context.data, start, stop });
    }

    loop(interval, context, func);
  }, interval);

  return { start, stop };
}

loop(1000, { state: "RUNNING", data: { counter: 0 } }, (options) => {
  const { stop, data } = options;
  data.counter += 1;
  console.log(data.counter);
  if (data.counter == 10) {
    stop();
  }
});

Metalwork

Answer 5

var x = true;
while(x){
   console.log("In loop")
}

Cleocleobulus

And what about the delay ? The while true is already in the question! – Bjork