View link click handler to get signed URL for the file.

gistfile1.js

function initEventHandlers() {
  // ...
  //
  $('#fileList').on('click', 'a.view-link', function() {
    var key = $(this).parents('li').data('key');
    bucket.getSignedUrl('getObject', { Key: key }, function (err, url) {
      window.open(url, '_blank');
    });
  });
}