app.component.ts

import { Component } from '@angular/core';
// Import SwUpdate from NGSW
import { SwUpdate } from '@angular/service-worker';

@Component({
  selector: 'app-root',
  template: `
    ...
  `,
  styles: []
})
export class AppComponent {
  title = 'app';

  // Inject SwUpdate
  constructor(private swUpdate: SwUpdate) {
    // Subscribe new worker is available
    this.swUpdate.available.subscribe(() => {
      if(window.confirm('新しいバージョンに更新しますか？')) {
        window.location.reload(true);
      }
    });
    // Check for new version
    this.swUpdate.checkForUpdate();
  }
}