Upload file in react App at UI side in folder

Hi I need to upload file in react which will be save in UI side in react folder.

for that I have written index.js to save the file in folder.

const express = require('express');
const app = express();
const multer = require('multer');
const cors = require('cors');

// setup multer for file upload
var storage = multer.diskStorage({
  destination: './build',
  filename: function (req, file, cb) {
    cb(null, file.originalname);
  },
});
app.use(
  cors({
    origin: '*',
  })
);

const upload = multer({ storage: storage });

app.use(express.json());

// serving front end build files
app.use(express.static(__dirname + '/../build'));

// route for file upload
app.post(
  'localhost:80/api/uploadfile',
  upload.single('myFile'),
  (req, res, next) => {
    console.log('FIle uploaded successfully');
    console.log(req.file.originalname + ' file successfully uploaded !!');
    res.sendStatus(200);
  }
);

app.listen(80, () => console.log('Listening on port 80'));

and my react ui app is.

import axios from 'axios';
import React, { Component } from 'react';
class FileUpload extends Component {
  state = {
    selectedFile: null,
  };

  onFileChange = (event) => {
    this.setState({ selectedFile: event.target.files[0] });
  };

  onFileUpload = () => {
    const formData = new FormData();
    formData.append('myFile', this.state.selectedFile);

    console.log(this.state.selectedFile);
    axios.post('http://localhost:80/api/uploadfile', formData, {
      headers: {
        'content-type': 'multipart/form-data',
      },
    }); //I need to change this line
  };
  fileData = () => {
    if (this.state.selectedFile) {
      return (
        <div>
          <h2>File Details:</h2>
          <p>File Name: {this.state.selectedFile.name}</p>
          <p>File Type: {this.state.selectedFile.type}</p>
          <p>
            Last Modified:{' '}
            {this.state.selectedFile.lastModifiedDate.toDateString()}
          </p>
        </div>
      );
    } else {
      return (
        <div>
          <br />
          <h4>Choose before Pressing the Upload button</h4>
        </div>
      );
    }
  };

  render() {
    return (
      <div>
        <h1>Plese select the translation file</h1>
        <div>
          <input type="file" onChange={this.onFileChange} />
          <button onClick={this.onFileUpload}>Upload!</button>
        </div>
        {this.fileData()}
      </div>
    );
  }
}

export default FileUpload;

my index.js and react app both are running on port 80. and my start script in package.json is

"start":dotenv -e .env -- webpack-dev-server --hot --define process.env.dev --inline --port 80 --host localhost

When I am saving file from UI then below error is coming

Can you guide me what mistake I am doing.