Setting dynamic page titles in an angular 2+ app.

titles.ts

  Step 1 #Provide a title in the route configuration,Usually in the app.module.ts
  	{ path: '', component: HomeComponent, data: { title: 'welcome' } },
  
 Step 2 #import {ActivatedRoute } from '@angular/router';
 Step 3 #Inject the ActivatedRoute interface in the constructor of your component:
 constructor(private router:ActivatedRoute) { }
  
 Step 4,#Subscribe to the data observable and pull out your data variables,use them for what you want.
  ngOnInit() {
     this.router.data.subscribe(data=> {
     # This does the job:
     document.title=data['title'];
     
     
  }
);
  }