title: Concatenate a variable in a string so as to form a URL
body: <p>I'm trying to consume an API which has to be specific for given users based on a variable: their cooker ID.</p>
  
  <p>As such, below is the script I wrote in order to achieve that: I'm parsing the variable as <code>${cookieuid}</code> in a string so as to form the URL;</p>
  
  <pre><code>getBellNotification() {
      let cookieuid = this.currentUser;
      let headers = new Headers();
      this.authorizeHeaders(headers);
      return this.http.get(
          this.config.apiUrl + 'api/supplier-notification/${cookieuid}?_format=json', {
              headers: headers
          }
      )
          .map(response =&gt; response.json())
          .catch(this.handleErrorObservable);
  }
  </code></pre>
  
  <p>It is not working as expected as I get the result below, with undesired special characters:</p>
  
  <pre><code>http://&lt;url&gt;/api/supplier-notification/$%7Bcookieuid%7D?_format=json
  </code></pre>
  
  <p>What am I doing wrong and how can I achieve that?</p>
  
  <p>I've tried other ways but still cannot get it working.</p>