code: function (r) {
              // If DONE (cancelled), then don't do anything
              if (me._readyState === FileReader.DONE) {
                  return;
              }
  
              // DONE state
              me._readyState = FileReader.DONE;
  
              if (r instanceof Array) {
                  r = new Uint8Array(r).buffer;
              }
              me._result = r;
  
              // If onload callback
              if (typeof me.onload === 'function') {
                  me.onload(new ProgressEvent('load', { target:me }));
              }
  
              // If onloadend callback
              if (typeof me.onloadend === 'function') {
                  me.onloadend(new ProgressEvent('loadend', { target:me }));
              }
          }
docs: Success callback