20/11/2017 Development / angular
<!-- Angular -->
<ul>
  <li *ngFor="let item of items; let i = index">
    {{i}} {{item}}
  </li>
</ul>
<ul>
  <li *ngFor=" let item of items; trackBy: trackByFn;">
    {{item}}
  </li>
</ul>
// Method in component class
trackByFn(index, item) {
  return item.id;
}