title: angular2. how can I make a route append queryParam with exists params?
body: <p>When I have URL : <a href="http://stack.com/abc?code=1" rel="nofollow noreferrer">http://stack.com/abc?code=1</a>
  And I would like to get URL like : <a href="http://stack.com/abc?code=1&amp;page=1" rel="nofollow noreferrer">http://stack.com/abc?code=1&amp;page=1</a></p>
  
  <p>I would like to use this kind of code</p>
  
  <pre><code>let navigationExtras;
  navigationExtras = {
    {preserveQueryParams: true},
    {queryParams: {page: 1}}
  };
  
  this.router.navigate(['/abc'], navigationExtras);
  </code></pre>
  
  <p>preserveQueryParams means using exists params.
  and queryParams means append new params.
  But using both at together are not work now.</p>
  
  <p>Any good idea? without using "this.route.subscribe(...)"</p>