ngOnInit() {
  this.router.changes.subscribe(changes => {
    console.log('location info:', this.location.platformStrategy.path());
  });
}

ngOnInit() {
  this.router.changes.subscribe(changes => {
    this.updatePath();
  });
}

updatePath() {
  this.path = this.location.platformStrategy.path();
  console.log('path updated:', this.path);
  this.appRef.tick();
}

<li><a [routerLink]="['/chat']" [ngClass]="{ 'active': path == '/chat' }">Chat</a></li>