Example of Promise chaining

promise-chaining.js

'use strict';
const Promise = require('bluebird');

class Test {
  constructor() {
    this.count = 0;
  }

  doSomething() {
    const self = this;
    console.log("Doing something");
    return new Promise((resolve, reject) => {
      self.count++;
      setTimeout(resolve, 1000)
    });
  }

  doSomethingElse() {
    const self = this;
    console.log("Doing something else");
    return new Promise((resolve, reject) => {
      self.count *= 2;
      setTimeout(resolve, 1000)
    });
  }

  printCount() {
    console.log("Final count: " + this.count);
  }
  
  run() {
    this.doSomething()
      .then(this.doSomethingElse.bind(this))
      .then(this.printCount.bind(this))
      .catch((err) => {
        console.error(err);
      });
  }
}

const t = new Test();
t.run();

// t.run() is async, so checking the count will give you a value
// at some point, but not the final answer
console.log("Random check on count: " + t.count);