nyks/function/promisify.js

"use strict";

/**
* Convert a node style fn to a promise
 */

module.exports = function(fn, ctx) {
  if(ctx === undefined)
    ctx = this;
  return function() {
    var args = [].slice.apply(arguments);

    return new Promise(function (resolve, reject) {
      args.push(function (err, res) {
        if(err)
          return reject(err);
        resolve(res);
      });
      fn.apply(ctx, args);
    });

  };
};