title: Using Fetch API to get flicker feed in json format
body: <p>I manage to get json response from flicker feed api by using $.getJSON, but when i try to do it using Fetch i only seems to get an XML response.</p>
  
  <p>This works:</p>
  
  <pre><code>var flickerAPI = "http://api.flickr.com/services/feeds/photos_public.gne?jsoncallback=?";
  $.getJSON(flickerAPI, {
                      tags: "searchTerm",
                      tagmode: "any",
                      format: "json"
                  })
                  .done(function (data) {
                     //....
                  });
  </code></pre>
  
  <p>This does not work:</p>
  
  <pre><code>var flickerAPI = "http://api.flickr.com/services/feeds/photos_public.gne?jsoncallback=?";
  
  var request = new Request(flickerAPI, { 
                  mode: 'no-cors',
                  tags: 'searchTerm',
                  tagmode: 'any',
                  format: 'json'
              });
  
              fetch(request)
                  .then(function (res) {
                      return res.json();
                  })
                  .then(function (text) {
                      console.log(text);
                  });
  </code></pre>
  
  <p>I also would like to understand why when using the Fetch API i am getting:
  "No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'null' is therefore not allowed access. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled." and when using  $.getJSON not.
  Thank you !!</p>