promises-promises-promises

async-auto.js

async.auto({
    get_data: function(callback){
        console.log('in get_data');
        // async code to get some data
        callback(null, 'data', 'converted to array');
    },
    make_folder: function(callback){
        console.log('in make_folder');
        // async code to create a directory to store a file in
        // this is run at the same time as getting the data
        callback(null, 'folder');
    },
    write_file: ['get_data', 'make_folder', function(callback, results){
        console.log('in write_file', JSON.stringify(results));
        // once there is some data and the directory exists,
        // write the data to a file in the directory
        callback(null, 'filename');
    }],
    email_link: ['write_file', function(callback, results){
        console.log('in email_link', JSON.stringify(results));
        // once the file is written let's email a link to it...
        // results.write_file contains the filename returned by write_file.
        callback(null, {'file':results.write_file, 'email':'[email protected]'});
    }]
}, function(err, results) {
    console.log('err = ', err);
    console.log('results = ', results);
});

basic-callback.js

fs.readFile('data.json', function(err, data) {
  if (err) // handle it
  try {
    var json = JSON.parse(data);
    render(json);
  }
  catch (e) { // handle it }}
});

callback-err.js

getUser(userId, function(err, user) {
  if (err) handleError(err);
  else {
    getUserFriends(user, function(err, friends) {
      if (err) handleError(err);
      else {
        getUserProfile(friends[0], function(err, json) {
          if (err) handleError(err);
          else {
            try { 
              var bestFriend = JSON.parse(json);
              refreshUi(bestFriend);
            }
            catch (Exception e) {
              handleError(e.message);
            }
          }
        });
      }
    });
  }
});

callbacks-compose.js

var squareCb = function(num, cb) {
  cb(null, num * num);
};

squareCb(2, function(err, num) {
  squareCb(num, function(err, result) {
    logIt(result);
  });
});

composability.js

var square = function(num) {
    return Promise.resolve(num * num); 
}

square(2).then(square).then(logIt);

going-deep.js

var nestedPromises = function() {
    return new Promise(function(resolve, reject) {
        new Promise(function(resolve2, reject2) {
            resolve2("Hello world");  
        }).then(resolve, reject)
    })
}

nestedPromises().then(logIt);

promise-err.js

getUser(userId)
  .then(function(user) {
    return getUserFriends(user);
  })
  .then(function(friends) {
    return getUserProfile(friends[0]);
  })
  .then(JSON.parse)
  .then(frefreshUi, handleError);

promise-to-composed.js

var square = function(num) {
    return num * num;
}

Promise.resolve(square(2)).then(square).then(logIt);

promises-auto.js

Promise
  .all([get_data, make_folder])
  .spread(function write_file(data, folder) { return 'filename'; })
  .then(function email_link(filename) {
    return sendEmail({file: filename});
  })
  .catch(function(err) { console.log(err); });

shared.js

logIt = console.log.bind(console)

wrapping.js

var Promise = require('bluebird');
// Entire library
var fs = Promise.promisifyAll(require('fs'));
fs.readFile('foo.json').then(JSON.parse).then(console.log.bind(console));

// Method
var request = Promise.promisify(require('request'));
request('http//foo.com/foo.json').then(JSON.parse).then(console.log.bind(console));