Create a pause inside a while loop in Javascript

Well, thanks to ES6-7 with Promises we can now make a pause and make it look nice at the same time!

var id = 0;

async function do() {
  while(true) {
    await pause(id);
    //will happen only after pause is done
    id++; 
  }
}
function pause(id) {
  return new Promise(resolve => setTimeout(() => {
    console.log(`pause ${id} is over`);
    resolve();
  }, 1500)); 
}

do();

setTimeout is a little trickier than that because it doesn't block (i.e. it doesn't finish waiting on the timeout before continuing with the program).

What you want is closer to this:

var i = 0;
function nextFrame() {
    if(i < n) {
        someanimation();
        i++;
        // Continue the loop in 3s
        setTimeout(nextFrame, 3000);
    }
}
// Start the loop
setTimeout(nextFrame, 0);

It may also be worth your while to read up on setInterval as a possible alternative.

setTimeout does not pause; it asks Javascript to run some other code later.

Googling for "setTimeout loop" tells you exactly what you need to know. If you look around a little bit, it even mentions setInterval. The difference: using setTimeout to loop will wait 3 seconds in between loops, whereas setInterval will make it take 3 seconds total for the loop (including however much time the animation takes, as long as it's less than 3 seconds :) ). Also, setInterval constructs an infinite loop that you'll have to break out of after the desired number of times; setTimeout requires you to construct the loop yourself.

i = 0;

// setTimeout approach
function animation_loop() {
  someAnimation();
  setTimeout(function() {
    i++;
    if (i < n) {
      animation_loop();
    }
  }, 3000);
};
animation_loop();

// setInterval approach
i = 0;
someAnimation();
iid = setInterval(function() {
  i++;
  if (i < n) {
    someAnimation();
  } else {
    clearInterval(iid);
  }
}, 3000);