Examples referenced in async js blog post

async-examples.js

// `series` Method Example

function eatFreeBread (bread, callback) {
  setTimeout(function () {
    console.log('Just ate some ' + bread + ' bread');
    callback(null, {breadRating: 8});
  }, 3000);
}

function eatAppetizers (apps, callback) {
  setTimeout(function () {
    console.log('Just ate these great appetizers ' + apps);
    callback(null, {appRating: 9});
  }, 3000);
}

function eatMainCourse (mainCourse, callback) {
  setTimeout(function () {
    console.log('Just ate the ' + mainCourse + ' main course');
    callback(null, {mainCourseRating: 9});
  }, 3000);
}

function eatDessert (dessert, callback) {
  setTimeout(function () {
    console.log('Just ate the ' + dessert + ' dessert');
    callback(null, {dessertRating: 10});
  }, 3000);
}

function handlePoorService () {
  console.log('WE ARE DONE WITH THIS NON SENSE AND ARE LEAVING!')
}

function goOutToEatV1 (bread, apps, mainCourse, dessert, restaurantReviewCallback) {

  eatFreeBread(bread, function (err, breadResult) {
    if (err) {
      handlePoorService();
      restaurantReviewCallback(err);
    } else {
      eatAppetizers(apps, function (err, appsResult) {
        if (err) {
          handlePoorService();
          restaurantReviewCallback(err);
        } else {
          eatMainCourse(mainCourse, function (err, mainCourseResult) {
            if (err) {
              handlePoorService();
              restaurantReviewCallback(err);
            } else {
              eatDessert(dessert, function (err, dessertResult) {
                if (err) {
                  handlePoorService();
                  restaurantReviewCallback(err);
                } else {
                  restaurantReviewCallback(null, [
                    breadResult,
                    appsResult,
                    mainCourseResult,
                    dessertResult
                  ]);
                }
              });
            }
          });
        }
      });
    }
  });
}

function goOutToEatV2 (bread, apps, mainCourse, dessert, restaurantReviewCallback) {
  async.series([
    function (callback) {
        eatFreeBread(bread, callback);
    },
    function (callback) {
        eatAppetizers(apps, callback);
    },
    function (callback) {
        eatMainCourse(mainCourse, callback);
    },
    function (callback) {
        eatDessert(dessert, callback);
    },
  ], function (err, restaurantResults) {
    if (err) {
      handlePoorService();
    }
    restaurantReviewCallback(err, restaurantResults);
  })
}

function goOutToEatV3 (bread, apps, mainCourse, dessert, restaurantReviewCallback) {
  async.series([
    _.curry(eatFreeBread)(bread),
    _.curry(eatAppetizers)(apps),
    _.curry(eatMainCourse)(mainCourse),
    _.curry(eatDessert)(dessert),
  ], function (err, restaurantResults) {
    if (err) {
      handlePoorService();
    }
    restaurantReviewCallback(err, restaurantResults);
  })
}

const bread = 'garlic';
const apps = ['rockefeller oysters', 'spinach and artichoke dip', 'bruschetta'];
const mainCourse = 'filet mignon';
const dessert = 'cheesecake';
const restaurantReviewCallback = function (err, results) { console.log('done with our review! ' + JSON.stringify(results)); };

// Uncomment to run different versions of the solution
// goOutToEatV1(bread, apps, mainCourse, dessert, restaurantReviewCallback);
// goOutToEatV2(bread, apps, mainCourse, dessert, restaurantReviewCallback);
// goOutToEatV3(bread, apps, mainCourse, dessert, restaurantReviewCallback);

// `each` Method Example
function sendEmail (emailAddress, email, callback) {
  setTimeout(function () {
    console.log('Sent the following email ' + email + ' to the following email address ' + emailAddress);
    callback(null, {emailId: Math.floor(Math.random() * 10000)});
  }, 3000);
}

function sendBatchOfEmailsV1 (emailAddresses, emailBody, callback) {
  var emailHasFailed = false,
      emailAddressIdx = 0,
      emailIds = [];

  while (!emailHasFailed && emailAddressIdx < emailAddresses.length) {

    sendEmail(emailBody, emailAddresses[emailAddressIdx], function (err, result) {
      if (err) {
        emailHasFailed = true;
        return callback(err);
      } else {
        emailIds.push(result.emailId);
      }

      if (emailIds.length === emailAddresses.length) {
        callback(null, emailIds);
      }
    });

    emailAddressIdx += 1;
  }
}

function sendBatchOfEmailsV2 (emailAddresses, emailBody, callback) {
  async.map(emailAddresses, function (emailAddress, asyncCallback) {
    sendEmail(emailBody, emailAddress, asyncCallback);
  }, callback);
}

function sendBatchOfEmailsV3 (emailAddresses, emailBody, batchCallback) {
  async.map(emailAddresses, _.curry(sendEmail)(email), batchCallback);
}

const email = 'Async.js Hello World!';
const emailAddresses = [
  'jdoe0@gmail.com',
  'jdoe1@gmail.com',
  'jdoe2@gmail.com',
  'jdoe3@gmail.com',
  'jdoe4@gmail.com',
  'jdoe5@gmail.com',
  'jdoe6@gmail.com',
  'jdoe7@gmail.com',
  'jdoe8@gmail.com',
  'jdoe9@gmail.com'
];
const batchEmailCallback = function (err, emailIds) { console.log('Batch email send result = ' + JSON.stringify(emailIds)); };

// Uncomment to run different versions of the solution
// sendBatchOfEmailsV1(emailAddresses, email, batchEmailCallback);
// sendBatchOfEmailsV2(emailAddresses, email, batchEmailCallback);
// sendBatchOfEmailsV3(emailAddresses, email, batchEmailCallback);

// `waterfall` Method Example
function makeReservation (reservationDetails, callback) {
  setTimeout(function () {
    console.log('Made the following reservation ' + JSON.stringify(reservationDetails));
    callback(null, Math.floor(Math.random() * 10000));
  }, 3000);
}

function processCreditCardForReservation (creditCardDetails, reservationId, callback) {
  setTimeout(function () {
    console.log('Charged the following reservation ' + reservationId + ' to the following card ' + JSON.stringify(creditCardDetails));
    callback(null, Math.floor(Math.random() * 10000));
  }, 3000);
}

function emailAirlineTicketReceipt (emailAddress, receiptId, callback) {
  setTimeout(function () {
    console.log('Emailed a receipt for receipt ID ' + receiptId + ' to the following email address ' + emailAddress);
    callback(null, Math.floor(Math.random() * 10000));
  }, 3000);
}

function bookAirlineTicketV1 (reservationDetails, creditCardDetails, receiptEmailAddress, bookAirlineTicketCallback) {
  makeReservation(reservationDetails, function (reservationErr, reservationId) {
    if (reservationErr) {
      bookAirlineTicketCallback(reservationErr);
    } else {
      processCreditCardForReservation(creditCardDetails, reservationId, function (creditCardProcessingError, receiptId) {
        if (creditCardProcessingError) {
          bookAirlineTicketCallback(creditCardProcessingError);
        } else {
          emailAirlineTicketReceipt(receiptEmailAddress, receiptId, function (emailError, emailId) {
              bookAirlineTicketCallback(emailError);
          });  
        }
      });
    }
  });
}

function bookAirlineTicketV2 (reservationDetails, creditCardDetails, receiptEmailAddress, bookAirlineTicketCallback) {
  async.waterfall([
      function(callback) {
          makeReservation(reservationDetails, callback);
      },
      function(reservationId, callback) {
          processCreditCardForReservation(creditCardDetails, reservationId, callback);
      },
      function(receiptId, callback) {
          emailAirlineTicketReceipt(receiptEmailAddress, receiptId, callback);
      }
  ], bookAirlineTicketCallback);
}

function bookAirlineTicketV3 (reservationDetails, creditCardDetails, receiptEmailAddress, bookAirlineTicketCallback) {
  async.waterfall([
    _.curry(makeReservation)(reservationDetails),
    _.curry(processCreditCardForReservation)(creditCardDetails),
    _.curry(emailAirlineTicketReceipt)(receiptEmailAddress),
  ], bookAirlineTicketCallback);
}

const reservationDetails = { destination: 'Cancun, Mexico', departureDate: '05/05/2018', airline: 'Delta' };
const creditCardDetails = { number: '1111111111111111', cvv: '123', zipcode: '12345' };
const receiptEmailAddress = 'jdoe@gmail.com';
const bookingCallback = function (err, results) { console.log('Flight has been booked!'); };

// Uncomment to run different versions of the solution
// bookAirlineTicketV1(reservationDetails, creditCardDetails, receiptEmailAddress, bookingCallback);
// bookAirlineTicketV2(reservationDetails, creditCardDetails, receiptEmailAddress, bookingCallback);
// bookAirlineTicketV3(reservationDetails, creditCardDetails, receiptEmailAddress, bookingCallback);