Blob to base64 converter

blob-to-base64-converter.js

<View style={{ flex: 1 }}>
  <Button
    title="download"
    onPress={() => {
      fetchFileAsPdf({...request})
      .then((response) => {
        // create a new file reader.
        const fileReader = new FileReader();
        // use readAsDataURL to read the contents of a Blob/File.
        fileReader.readAsDataURL(response);
        // triggered when the read operaiton is finished.
        fileReader.onloadend = function () {
        const base64data = fileReader.result;
        // Remove the preamble data:*/*;base64, to get the exact encoded base64. Else it won't work.
        const filteredBase64 = base64data.split(',')[1];
        const { fs } = RNFetchBlob;
        const { DownloadDir } = fs.dirs;
        // choose the directory and write the base64 data to a file.
        RNFetchBlob.fs
        .writeFile(`${DownloadDir}/Invoice.pdf`, filteredBase64, 'base64')
        .then(res => console.log('File :: ', res))
        .catch(err => console.log('Error in writing file :: ', err));
        };                  
      })
      .catch(err => console.log('Error in downloading :: ', err));
    }}
  />
</View>