ES6 untangling callback 🍝

spawn.js

'use strict';

const fs = require('fs');

function spawn(generator) {
  let it = generator(function (err, data) {
    if (err) it.throw(err);
    return it.next(data);
  });
  it.next();
}

function main() {
  spawn(function* (resume) {
    let content = yield fs.readFile(__filename, resume);
    yield fs.writeFile(__dirname + '/dup.js', content, resume);
  });
}

if (require.main === module) { main(); }