promisify.js

//promisify.js
module.exports = (func, bound = null) => (...args) => new Promise(
  (resolve, reject) => func.call(bound, ...args, (err, ...results) => err ? reject(err) : resolve(...results))
);


/****************************************************************************************
 * This function is used to turn a callback style function into an await(able) result.
 *
 * For example, fs.readFile takes two parameters: fs.readFile(name, callback);
 * 
 * Callback needs to look like this: function(error, result)
 ****************************************************************************************/

fs.readFile(name, function(error, result) {
  if (err)
    return console.log(error);
  console.log(result);
});

// What if instead we wrapped the fs.readFile function with promisify and used the await keyword in an async function?


(async function() {
  'use strict';
  let readFile = promisify(fs.readFile);
  
  let result = await readFile(name);
  console.log(result);
}())