MyWebPartWithEventBus.ts

import * as ko from 'knockout';
// ...other imports omitted...

import { EventBus } from './EventBus';

let _instance: number = 0;

export default class CoffeeRoundWebPart extends BaseClientSideWebPart<any> {
  private _id: number;
  private eventBus = EventBus.getInstance();

  public constructor(context: IWebPartContext) {
    super(context);
    this._id = _instance++;
  }

  private initWorkaround():void{
    const tagName: string = `CoffeeRoundComponent-${this._id}`;
    const componentElement: HTMLElement = this._createComponentElement(tagName);
    this._registerComponent(tagName);
    this.domElement.appendChild(componentElement);

    var vm = new CoffeeRoundViewModel();
    ko.applyBindings(vm, this.domElement);
  }

  public render(): void {
    console.log('render');

    if (!this.renderedOnce)
    {
      this.initWorkaround();
    }

    // push vals into eventbus with new values
    this.eventBus.myProp(this.properties.myProp || '');
  }
}