‹div›
  Pick your favorite hero
  (‹label›‹input type="checkbox" checked (change)="showSad = !showSad"›show sad‹/label›)
‹/div›
‹select [(ngModel)]="hero"›
  ‹span *ngFor="let h of heroes"›
    ‹span *ngIf="showSad || h.emotion !== 'sad'"›
      ‹option [ngValue]="h"‹h.name}} ({{h.emotion}})‹option›
    ‹/span›
  ‹/span›
‹/select›