shaikh-shahid

var async = require('async');

// Send email
var sendEmail = function(email,callback) {
  console.log("Sending email to "+email);
  callback(null);
}

// create a queue object with concurrency 2
var q = async.queue(sendEmail,2);

shaikh-shahid

var async = require('async');

async.forEach(someData,function(singleData,callback){
  async.series();
  //OR
  async.paralle();
  //OR
  async.waterfall();
},function(err,data) {
  // final callback

shaikh-shahid

var async = require('async');
var emails = ["[email protected]","[email protected]"];

async.each(emails,function(singleEmail,callback) {
  async.waterfall([
    function(callback) {
      // code to send email.
      callback(null,Flag);
    },
    function(emailSentOrNot,callback) {

shaikh-shahid

var async = require('async');
var emails = ["[email protected]","[email protected]"];

async.eachLimit(emails,1000,function(singleEmail,callback) {
  // Emailer code
  // singleEmail will be one value at a time.
},function(err,data) {
  // Once all done, comes here.
});

shaikh-shahid

var async = require('async');
var emails = ["[email protected]","[email protected]"];

async.each(emails,function(singleEmail,callback) {
  // Emailer code
  // singleEmail will be one value at a time.
},function(err,data) {
  // Once all done, comes here.
});

shaikh-shahid

var async = require('async');

async.waterfall([
    function(callback) {
      // some code to execute
      // in case to go to next function provide callback like this.
      callback(null,valueForNextFunction);
      // Got some error ? Don't wanna go further.
      // Provide true in callback and execution will stop.
      //callback(true,"Some error");

shaikh-shahid

var async = require('async');

async.series([
    function(callback) {
      // some async task
      callback();
    },
    function(callback) {
      // some async task
      callback();

shaikh-shahid

var async = require('async');

async.parallel([
    function(callback) {
      // Some Async task
      callback();
    },
    function(callback) {
      // Some Async task
      callback();

shaikh-shahid

var EventEmitter = require('events').EventEmitter;
var emitter = new EventEmitter();
var fs = require('fs');
// Event to read file - generic function.
emitter.on('start_read',function(file_name) {
  console.log("Started Reading file....\n\n");
  fs.readFile(file_name, 'utf8', function (err,data) {
    if (err) {
      console.log("Error happens.");
    } else {

shaikh-shahid

var Promise = require('bluebird');
 // Converts all function of 'fs' into promises.
var fs = Promise.promisifyAll(require('fs'));

fs.readFileAsync('file.js','utf8')
// 'then' when result comes.
.then(function(data) {
  console.log(data);
})
//'catch' when error comes.