node12 --harmony denodeify

denodeify.js

var denodeify = function (fn) {
	return function () {
		var that = this;
		var args = [].slice.call(arguments);
		return new Promise(function (resolve, reject) {
			args.push((err, res) => err ? reject(err) : resolve(res));
			fn.apply(that, args);
		})
	}
}