Using a Queue to contain our data structure, use a queue. Create a function that returns our data in a plain old Object. A queue is a collection of items that obey's the principle of FIFO, first in, first out.

createQueue.js

function createQueue() {
  // store our queue
  const queue = []

  return {
    // add or enqueue
    enqueue(item) {
      queue.unshift(item)
    },
    // remove or dequeue
    dequeue() {
      if (queue.length === 0) {
        return undefined
      }
      return queue.pop()
    },
    // look or peek
    peek() {
      if (queue.length === 0) {
        return undefined
      }
      return queue[queue.length - 1]
    },
    // use a getter function to get the length of the queue
    get length() {
      return queue.length
    },
    // check to see if queue is empty
    isEmpty() {
      return queue.length === 0
    }
  }
}