Angular: append query parameters to URL

I had to adjust Jota.Toledos answer a bit so that it works for me, I had to take out the second and the last property of the extras - object:

   navigateToFoo(){
     this._router.navigate([], {
      queryParams: {
        newOrdNum: '123'
      },
      queryParamsHandling: 'merge',
    });
   }

You should write

let params = new HttpParams();
params = params.append('newOrdNum','123');

This could be achieved by using the Router class:

Using a component:

import { Router, ActivatedRoute } from '@angular/router';

@Component({})
export class FooComponent {
   constructor(
     private _route: ActivatedRoute,
     private _router: Router
   ){}

   navigateToFoo(){
     // changes the route without moving from the current view or
     // triggering a navigation event,
     this._router.navigate([], {
      relativeTo: this._route,
      queryParams: {
        newOrdNum: '123'
      },
      queryParamsHandling: 'merge',
      // preserve the existing query params in the route
      skipLocationChange: true
      // do not trigger navigation
    });
   }
}

For more info check this book and the angular Router API