frontend-tutorial-framework/src/app/dashboard/dashboard.component.ts

import { Component, OnDestroy, OnInit } from '@angular/core';
import { DeploymentNotificationService } from '../services/deployment-notification.service';
import { Subscription } from 'rxjs/Subscription';

@Component({
  selector: 'app-dashboard',
  templateUrl: './dashboard.component.html',
  styleUrls: ['./dashboard.component.scss']
})
export class DashboardComponent implements OnInit, OnDestroy {

  deploying = false;
  deploymentNotificationSubscription: Subscription;

  constructor(private deploymentNotificationService: DeploymentNotificationService) {}

  ngOnInit() {
    this.deploymentNotificationSubscription = this.deploymentNotificationService.deploying.subscribe(
      (deploying) => this.deploying = deploying
    );
  }

  ngOnDestroy() {
    if (this.deploymentNotificationSubscription) {
      this.deploymentNotificationSubscription.unsubscribe();
    }
  }
}