params with new URL code example

Example: url param

// ...
import { ActivatedRoute } from '@angular/router';
import 'rxjs/add/operator/filter';

@Component({ ... })
export class BookComponent implements OnInit {
  
  category: string;
  
  constructor(private route: ActivatedRoute) { }

  ngOnInit() {
    this.route.queryParams
      .filter(params => params.category)
      .subscribe(params => {
        console.log(params); // { category: "fiction" }
        this.category = params.category;
        console.log(this.category); // fiction
      }
    );
  }
}