Execute operations with delay time between them

Poller.js

const Poller = (time, callback) => {
  const queue = [];
  
  const add = op => {
    queue.push(op)
  }
  
  const exec = () => {
    callback(queue.shift())
    
    if (queue.length) {
      setTimeout(() => exec(), time)
    }
  }
  
  return {
    add, exec
  }
}

const poller = Poller(1000, console.log)
poller.add(1)
poller.add(2)
poller.add(3)
poller.exec()