Manual Promise Resolution and Rejection with Bluebird and Q

Bluebird Manual Promise

var Promise = require('bluebird');

var fetchPostById = function(postId){
  return new Promise(function(resolve, reject){
    mySampleAsyncDatabaseFetch(postId, function(err, post){
      if(err){
        reject(err);
      }
      resolve(post);
    });
  });
};

//later you can do

fetchPostById(1234).then(function(post){
  console.log("Found post 1234");
  console.log(post);
}).catch(function(err){
  console.log("Wow something seriously went wrong!");
  console.log(err);
});

Q Manual Promise

var Q = require('Q');

var fetchPostById = function(postId){
  var deferred = Q.defer();
    mySampleAsyncDatabaseFetch(postId, function(err, post){
      if(err){
        deferred.reject(err);
      }
      deferred.resolve(post);
    });
  return deferred.promise;
};

//later you can do

fetchPostById(1234).then(function(post){
  console.log("Found post 1234");
  console.log(post);
}, function(err){
  console.log("Wow something seriously went wrong!");
  console.log(err);
});