title: express res.send as result of promise
body: <p>I'm not understanding what's going on...</p>
  
  <p>Using <code>q</code> promises, this works:</p>
  
  <pre><code>const deferred = q.defer();
  deferred.resolve('Hellow');
  
  const myPromise = deferred.promise;
  
  router.get('/items', (req, res) =&gt; {
      myPromise.then((result) =&gt; res.send(result));
  });
  </code></pre>
  
  <p>but this doesn't, it keeps the browser like if the request never ends:</p>
  
  <pre><code>router.get('/items', (req, res) =&gt; {
      myPromise.then(res.send);
  });
  </code></pre>
  
  <p>What's wrong?</p>