title: Get json from jsonp fetch promise
body: <p>I am just starting with react-native, and I'm doing the classic example in the docs as a base...</p>
  
  <pre><code>fetch('https://facebook.github.io/react-native/movies.json')
    .then((response) =&gt; response.json())
    .then((responseJson) =&gt; {
      return responseJson.movies;
    })
    .catch((error) =&gt; {
      console.error(error);
    });
  </code></pre>
  
  <p>This all works fine with proper json in that example.</p>
  
  <p>However, in my particular case, the only api response available is JSONP and not JSON. No basic JSON is available. So I receive an error about the "(".</p>
  
  <p>So instead of JSON like</p>
  
  <pre><code>{"id": "1", "movies" : [ { "id" : "123" } ] }
  </code></pre>
  
  <p>I receive JSONP like</p>
  
  <pre><code>?( {"id": "1", "movies" : [ { "id" : "123" } ] });
  </code></pre>
  
  <p>However, I'm unsure what I can do to get the JSON out of this via the fetch promises ? How can I manipulate the response with one of my own functions, or is there a more natural way ?</p>
  
  <p>So in the first then() I'm unsure what I can do to get out the json (I've tried operating on the response, but that just seems to look at the promise, so I'm unsure how react-native fetch is operating with this).</p>