defer requests

controllers.application.js

import Controller from '@ember/controller';
import { A } from '@ember/array';
import { computed } from '@ember/object';
import { later } from '@ember/runloop';
import { Promise } from 'rsvp';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  deferredRequests: computed(() => A()),
  requestCount: 0,
  actions: {
    start() {
      let deferredRequest = {
        handler: null,
        id: this.get('requestCount'),
        mayResolve: false,
        resolve: () => {}
      };
      deferredRequest.handler = new Promise((resolve) => {
        deferredRequest.resolve = resolve;
        later(() => {
          if (deferredRequest.mayResolve) {
            this.get('deferredRequests').removeObject(deferredRequest);
            resolve('after 2ms');
          } else {
            deferredRequest.mayResolve = true;
          }
        }, 2000);
      }).then((type) => {
        console.log(`request ${deferredRequest.id} resolved: ${type}`);
      });
      this.get('deferredRequests').pushObject(deferredRequest);
      this.incrementProperty('requestCount');
    },
    resolve() {
      console.log(`${this.get('deferredRequests')} requests deferred`);
      let resolvedRequests = [];
      this.get('deferredRequests').forEach((deferredRequest) => {
        if (deferredRequest.mayResolve) {
          console.log(`resolve ${deferredRequest.id} now`);
          // must remove the items of array after looping has finished
          // otherwise some item of the array are skipped
          resolvedRequests.push(deferredRequest);
          deferredRequest.resolve('after additional time');
        } else {
          console.log(`resolve ${deferredRequest.id} later`);
          deferredRequest.mayResolve = true;
        }
      });
      this.get('deferredRequests').removeObjects(resolvedRequests);
    }
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
Pending requests: {{deferredRequests.length}}
<br>
<button onclick={{action 'start'}}>start</button>
<button onclick={{action 'resolve'}}>resolve</button>
<br>
<br>

twiddle.json

{
  "version": "0.15.0",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.2.2",
    "ember-template-compiler": "3.2.2",
    "ember-testing": "3.2.2"
  },
  "addons": {
    "ember-data": "3.2.0"
  }
}