Convert Node callback to Promise

callback_as_promise.js

function callbackAsPromise(fn, scope) {
  return function() {
    var args = Array.prototype.slice.apply(arguments);
    return new Promise(function(resolve, reject) {
      fn.apply(scope, args.concat(function(err, data) {
        if (err) reject(err);
        resolve(data);
      }));
    });
  }
}
// Example:
// var readFile = callbackAsPromise(fs.readFile, fs);