how to send and receive file by flask and axios

function downloadFile(src, dst) {
  axios
    .get(src, { responseType: 'stream' })
    .then(async resp => {
      resp.data.pipe(fs.createWriteStream(dst));
    });
}

downloadFile(
  'http://localhost:5000/download/test.jpeg',
  'result.jpeg'
);

@app.route('/download/')
def download(filename):
    return send_from_directory(app.static_folder, filename)

function downloadFile(src, dst) {
  const url = 'http://localhost:5000/send';
  const formData = new FormData();
  formData.append('filename', src);
  axios
    .post(url, formData, { headers: formData.getHeaders(), responseType: 'stream' })
    .then(async resp => {
      resp.data.pipe(fs.createWriteStream(dst));
    });
}

downloadFile(
  'test.jpeg',
  'result.jpeg'
);

const url = 'http://localhost:5000/upload';
const filePath = path.resolve('result.jpeg');
fs.readFile(filePath, async (error, data) => {
  if (error) {
    console.log(error);
    return;
  }
  const formData = new FormData();
  formData.append('file', data, { filepath: filePath, contentType: 'image/jpg' });
  axios
    .post(url, formData, { headers: formData.getHeaders() })
    .then(resp => {
      console.log('File uploaded successfully.');
    });
});

@app.route('/upload', methods=['POST'])
def upload():
    file = request.files.get('file');
    # Process the file here.
    return '', 200

from flask import send_file
import json

@app.route('/send')
def send_json_binary():
    filename = 'test.jpeg'
    resp = send_file(filename, mimetype='image/jpeg')
    resp.headers['X-Metadata'] = json.dumps({
        'filemeta': 'Your metadata here.'
    })
    return resp

function downloadFile(src, dst) {
  axios
    .get(src, { responseType: 'stream' })
    .then(async resp => {
      const meta = JSON.parse(resp.headers['x-metadata'])
      const filemeta = meta.filemeta;
      resp.data.pipe(fs.createWriteStream(dst));
    });
}

downloadFile(
  'http://localhost:5000/send',
  'result.jpeg'
);

from flask import jsonify
from base64 import b64encode

@app.route('/sample')
def send_json_binary():
    filename = 'test.jpeg'
    with open(filename, 'rb') as fh:
        return jsonify(
            filemeta = 'Your metadata here.',
            filedata = b64encode(fh.read()).decode()
        )

function downloadFile(src, dst) {
  axios
    .get(src, { responseType: 'json' })
    .then(async resp => {
      const meta = resp.data.filemeta;
      const buffer = Buffer.from(resp.data.filedata, 'base64');
      const stream = Readable.from(buffer);
      stream.pipe(fs.createWriteStream(dst))
    });
}

downloadFile(
  'http://localhost:5000/send',
  'result.jpeg'
);