title: "which is disallowed for cross-origin requests that require preflight" error in passport facebook login?
body: <p>I have a node.js express app which provides RESTful APIs and I'm using passport for Facebook authentication. I enabled all CORS configuration in the server side and was able to consume APIs via jQuery Ajax. But for Facebook authentication I'm getting the following error:</p>
  
  <pre><code>XMLHttpRequest cannot load http://localhost:3000/auth/facebook. The request was redirected to 'https://www.facebook.com/dialog/oauth?response_type=code&amp;redirect_uri=http%…_me%2Cuser_checkins%2Cuser_likes&amp;client_id=12345678&amp;type=web_server', which is disallowed for cross-origin requests that require preflight. 
  </code></pre>
  
  <p>/auth/facebook endpoint is this.</p>
  
  <pre><code>app.get('/auth/facebook',
      passport.authenticate('facebook', {
          scope: ['email', 'user_about_me', 'user_checkins', 'user_likes'],
          failureRedirect: users.authFailCallback
      }), users.signin);
  </code></pre>
  
  <p>So basically it is redirected to Facebook's API (302) which does not allow CORS.
  Is there any way to solve this? Or I need to call Facebook APIs from server side itself?</p>