🧑‍💻 Scheduling

Scheduled Counter

A function that calls a given function n times at interval ms apart, starting from 0. 

function createCounter(func, n, interval) {
  let count = 0;

  return function counter() {
    func(count++);
    if (count < n) {
      setTimeout(counter, interval);
    }
  };
}

const startCounter = createCounter(console.log, 10, 500);
startCounter();
Output: 
0
1
2
3
4
5
6
7
8
9

Timeout Reset Wrapper

A wrapper that delays the execution of a function until after a specified timeout has passed since the last call, resetting the timer with each call. 
function createTimeoutWrapper(func, timeout) {
  let id = null;

  return function() {
    clearTimeout(id);
    id = setTimeout(func, timeout);
  }
}

const wrapper = createTimeoutWrapper(() => console.log('Hello!'), 1000);
console.log('Calling wrappers.');
wrapper();
wrapper();
wrapper();
wrapper();
wrapper();
console.log('Multiple wrappers called.');
Output: 
Calling wrappers.
Multiple wrappers called.
Hello!

Custom setInterval

A custom version of setInterval using recursive setTimeout. 
function setMyInterval(func, interval) {
  const id = { value: null };

  (function callback() {
    id.value = setTimeout(() => {
      func();
      callback();
    }, interval);
  })();

  return id;
}

function clearMyInterval(id) {
  clearTimeout(id.value);
}

const id = setMyInterval(() => {
  console.log('tick');
}, 1000);

setTimeout(() => clearMyInterval(id), 5000);
Output: 
tick
tick
tick
tick

Timer object

A Timer class that repeatedly calls a function with an incrementing counter at set intervals, and allows pausing and resuming the timer using pause and continue methods. 
function Timer(func, interval) {
  let id = null;
  let counter = 0;

  this.pause = function() {
    clearInterval(id);
  }

  this.start = this.continue = function() {
    id = setInterval(() => {
      func(counter++);
    }, interval);
  }
}

const timer = new Timer(console.log, 1000);

console.log('Starting timer at 0s.');
timer.start();

setTimeout(() => {
  console.log('Pausing timer at 5s.');
  timer.pause();
}, 5010);

setTimeout(() => {
  console.log('Continuing timer at 10s.');
  timer.continue();
}, 10000);

setTimeout(() => {
  console.log('Pausing timer at 15s.');
  timer.pause();
}, 15010);
Output: 
Starting timer at 0s.
0
1
2
3
4
Pausing timer at 5s.
Continuing timer at 10s.
5
6
7
8
9
Pausing timer at 15s.