demo.html

<html>
  <body>
    <script src="dist/filepreviews.js"></script>
    <script type="text/javascript">
      var previews = new FilePreviews({
        debug: true,
        apiKey: 'XRoVCJFm8a1PhwRAJ4IZFEKnnNZ35F'
      });

      var url = 'http://i.imgur.com/HvAx8vL.jpg';
      var options = {
        size: {
          width: 100,
          height: 999
        },
        metadata: ['exif', 'ocr', 'psd'],
        format: 'jpg'
      };

      previews.generate(url, options, function(err, result) {
        if (err) {
          return console.error(err);
        }

        previews.retrieve(result.id, function(err, result) {
          if (err) {
            return console.error(err);
          }

          console.log(result);
        });
      });

      previews.generate(url, function(err, result) {
        if (err) {
          return console.error(err);
        }

        console.log(result);
      });

      previews.generate(url, options);

      previews.generate(url);
    </script>
  </body>
</html>