title: Angular : This type is not supported as injection token
body: <p>I'am trying to create a constructor with type <code>string</code> but I'am getting the error as:</p>
  <blockquote>
  <p>This type is not supported as injection token</p>
  </blockquote>
  <pre class="lang-js prettyprint-override"><code>@Injectable({providedIn: 'root'})
  export class DataService {
       constructor(url:string, private http:HttpClient) { 
       }
  }
  
  export class PostService extends DataService {
      constructor(http:HttpClient) {
           super(&quot;https://jsonplaceholder.typicode.com/posts&quot;,http);
      }
   }
  </code></pre>