index.html

<!DOCTYPE html>
<html lang="en" dir="ltr">
  <head>
    <meta charset="utf-8">
    <title>Testing Copy</title>
  </head>
  <body>
    <button type="button" name="button">Attempt Copy</button>
    <script type="text/javascript">
      const path = require('path');
      const fs = require('fs');
      const { app } = require('electron').remote;

      const button = document.querySelector('button');
      const src = path.join(__dirname, 'test.txt');
      const dest = path.join(app.getPath('home'), 'test.txt');

      console.log(`Target location: ${dest}`);

      button.addEventListener('click', () => {
        fs.readdir(path.dirname(src), (err, files) => console.log(`Files in source: ${files}`));
        fs.copyFile(src, dest, err => err ? console.error(err) : 0);
      });
    </script>
  </body>
</html>