title: Javascript blocking on post request
body: <p>I have, what I believe to be a pretty normal and sane javascript function, below:</p>
  
  <pre><code>$scope.pickFile = function() {
      filepicker.setKey("...");
      filepicker.pick(
          {},
          function(Blob) {  // OnSuccess
              var uuid = Blob.url.split('/').slice(-1)[0];
              window.location.replace("/url" + uuid);
              $.post(
                  "/other_url" + uuid,
                  {'input': $('#rawText')[0].checked? "text" : "features"}
              );
      });
  }
  </code></pre>
  
  <p>Now, the bizarre thing is that the redirect doesn't happen until the post request finishes. My gut says this might be some magic happening behind the scenes with filepicker, but I have no idea what it might be, and there doesn't seem to be any documentation around it.</p>
  
  <p>It doesn't seem to be simple synchronicity either since the redirect is actually first, but it is blocking on the post request completing.</p>