Diff between native promise & $.Deferred promise chain

promise_and_deferred.js

// Check the console logs by uncommenting the error throwing scenario also

function one() {
  console.log('one')
  throw new Error('error1')
}

function two() {
  console.log('two')
}

function three() {
  console.log('three')
}

function errorHandlerOne(err) {
  console.log('Error1', err)
  // throw err //uncomment this line to check error bubbling chain
}

function finalErrorHandler(err) {
  console.log('Final Error', err)
}

// Synchronous
try {
  console.log(`------- Synchronous flow -------`)
  try {
    one()
    two()
  } catch (e) {
    errorHandlerOne(e)
  }
  three()
} catch (e) {
  finalErrorHandler(e)
}

// Native Promises
let someAsync = () => {
  return new Promise((resolve, reject) => {
    setTimeout(function() {
      console.log(`------- Native Promise Chain -------`)
      resolve()
    }, 500)
  })
}

someAsync()
  .then(one)
  .then(two)
  .catch(errorHandlerOne)
  .then(three)
  .catch(finalErrorHandler)


// $.Deferred promise
function deferredAsync () {
  let deferred = $.Deferred()  
  setTimeout(function() {
    console.log(`------- $.Deferred Promise Chain -------`)
    deferred.resolve()
  }, 500)
  return deferred
}

deferredAsync()
  .then(one)
  .then(two)
  .fail(errorHandlerOne)
  .then(three)
  .fail(finalErrorHandler)