title: Chaining promises in ES6/Typescript
body: <p>I need to chain promises to make several GET requests and combine the data before using it elsewhere. I am having difficulty resolving the two promises. I've tried returning an array of the two promises before trying to use <code>.json()</code> but that doesn't work either.</p>
  
  <pre><code>activate() {
  
      // data is from http://jsonplaceholder.typicode.com/photos and
      // since there is not a photos2/ endpoint this is conceptual and 
      // represents batch importng
      return Promise.all([
          this.http.fetch('photos'),
          this.http.fetch('photos2')
      ]).then(responses =&gt; {
  
          console.log(responses); // see block of code below this for output
  
          // how can I combine the two promises here so I can resolve them with 'then' below?
          return responses[0].json(); // can return one response
          // return responses; //  doesn't work
  
      }).then(data =&gt; {
          console.log(data);
          this.photos = data;
  
      }).catch(err =&gt; {
          console.log(err);
      });
  }
  </code></pre>
  
  <p>output of console.log(responses); :</p>
  
  <pre><code>[Response, Response]
  0: Response
  body: (...) // readablebytestream
  bodyUsed : false
  headers : Headers
  ok : true
  status : 200
  statusText : "OK"
  type : "cors"
  url : "http://jsonplaceholder.typicode.com/photos"
  __proto__ : Object
  1 : Response
   ....etc
  </code></pre>
  
  <p>Thank you!</p>