node-promisify-simple-callback/lib/index.js

'use strict';

var Promise = require("bluebird");

module.exports = function (method) {
	var defaults = arguments.length <= 1 || arguments[1] === undefined ? [] : arguments[1];

	return function () {
		var _this = this;

		var originalArgs = new Array(arguments.length);

		for (var i = 0; i < originalArgs.length; ++i) {
			originalArgs[i] = arguments[i];
		}

		return new Promise(function (resolve, reject) {
			var args = new Array(Math.max(originalArgs.length, defaults.length) + 1);

			for (var i = 0; i < originalArgs.length; ++i) {
				args[i] = originalArgs[i];
			}

			if (originalArgs.length < defaults.length) {
				for (var i = originalArgs.length; i < defaults.length; i++) {
					if (defaults[i] != null) {
						args[i] = defaults[i];
					}
				}
			}

			args[args.length - 1] = function (result) {
				resolve(result);
			};

			// Synchronous errors are caught and propagated by Bluebird's `new Promise` already.
			method.apply(_this, args);
		});
	};
};