ES2015 function queue

queue.js

"use strict";


class Queue {
  constructor() {
    this.running = false;
    this.items = [];
  }

  enqueue(fn) {
    return new Promise((resolve, reject) => {
      this.items.push(() => {
        return fn().then(resolve, reject);
      });
      this.run();
    });
  }

  run() {
    if (!this.running && 0 < this.items.length) {
      this.running = true;
      this.items.shift()().then(() => {
        this.running = false;
        this.run();
      }, () => {
        this.running = false;
        this.run();
      });
    }
  }
}

module.exports = Queue;