import { ChangeDetectionStrategy , Component } from '@angular/core' ; import { FormBuilder , FormGroup } from '@angular/forms' ; @ Component ( { selector : 'app-radio-page' , templateUrl : './radio-page.component.html' , changeDetection : ChangeDetectionStrategy . OnPush } ) export class RadioPageComponent { favoriteSeason = 'Spring' ; secondFavoriteSeason = 'Summer' ; disabled = false ; seasons = [ 'Winter' , 'Spring' , 'Summer' , 'Autumn' ] ; season : string ; form : FormGroup ; constructor ( fb ) { this . form = fb . group ( { season : 'Spring' } ) ; } }