selfsame

  var fs = {
    read: (filename, cb, err) => {
      navigator.webkitPersistentStorage.requestQuota(0, (bytes) => {
        window.webkitRequestFileSystem(PERSISTENT, bytes, (fs) => {
          fs.root.getFile(filename, {},
            (entry) => {
              entry.file((file) => {
                var reader = new FileReader();
                if(err)
                  reader.onerror = err;