listen change from parent to child event angular code example
Example: angualar subscribe parent event
content_copy
import { Component } from '@angular/core';
import { MissionService } from './mission.service';
@Component({
selector: 'app-mission-control',
template: `
<h2>Mission Control</h2>
<button (click)="announce()">Announce mission</button>
<app-astronaut *ngFor="let astronaut of astronauts"
[astronaut]="astronaut">
</app-astronaut>
<h3>History</h3>
<ul>
<li *ngFor="let event of history">{{event}}</li>
</ul>
`,
providers: [MissionService]
})
export class MissionControlComponent {
astronauts = ['Lovell', 'Swigert', 'Haise'];
history: string[] = [];
missions = ['Fly to the moon!',
'Fly to mars!',
'Fly to Vegas!'];
nextMission = 0;
constructor(private missionService: MissionService) {
missionService.missionConfirmed$.subscribe(
astronaut => {
this.history.push(`${astronaut} confirmed the mission`);
});
}
announce() {
const mission = this.missions[this.nextMission++];
this.missionService.announceMission(mission);
this.history.push(`Mission "${mission}" announced`);
if (this.nextMission >= this.missions.length) { this.nextMission = 0; }
}
}