Util#promisify #async-await #medium

promisifying.js

const fs = require('fs');
const { promisify } = require('util');

// Function#bind as needed
const readFile = promisify(fs.readFile);
const writeFile = promisify(fs.writeFile);

const transform = () => /* ... */;

const transformFileAsync = async (source, dest) => {
  const data = await readFile(source);
  // Do some transformation
  const transformedData = tranform(data);
  
  await writeFile(dest, transformedData);
};

transformFileAsync('x.js', 'y.js').then(...).catch(...);