gistfile1.js

var Promise = require('bluebird');

function Micro (id) {
  this.id = id;
}

Micro.prototype.connect = function () {
  return new Promise(function (fulfill, reject) {
    setTimeout(function() {
      if (Math.random() > 0.5)
        fulfill(this.id);
      else
        reject(new Error('failed'));
    }.bind(this), 1000);                    // Note the bind calls to provide 'this' to the nested callbacks
  }.bind(this));                            // Otherwise, this.id would be undefined in the setTimeout callback
                                            //                            where you would expect it to be 100
}

//
//

var mc = new Micro(100);
mc.connect()
  .then(console.log)
  .catch(console.error);