// https://github.com/elasticsales/s3upload-coffee-javascript
var s3upload = new S3Upload({
  file_dom_selector: '#files', // an <input type="file"> element
  s3_sign_put_url: '/sign_s3_put',
  onProgress: function(percent, message, publicUrl, file) { // Use this for live upload progress bars
    console.log('Upload progress: ', percent, message);
  },
  onFinishS3Put: function(public_url, file) { // Get the URL of the uploaded file
    console.log('Upload finished: ', public_url);
  },
  onError: function(status, file) {
    console.log('Upload error: ', status);
  }
});