deferred promise .then()

gistfile1.js

function fooA(){
  console.log('exec fooA');
  var dfd = new $.Deferred();
  dfd.done(function() {
    console.log('fooA Success');
  })
  .fail(function() {
    console.log('fooA fail');
  });
  setTimeout(dfd.reject, 0);
  return dfd.promise();
}


function fooB(){
  console.log('exec fooB');
  var dfd = new $.Deferred();
  dfd.done(function() {
    console.log('fooB Success');
  })
  .fail(function() {
    console.log('fooB fail');
  });
  //reject here
  setTimeout(dfd.resolve, 0);
  return dfd.promise();
}

function fooC(){
  console.log('exec fooC');
  var dfd = new $.Deferred();
  dfd.done(function() {
    console.log('fooC Success');
  })
  .fail(function() {
    console.log('fooC fail');
  });
  setTimeout(dfd.resolve, 0);
  return dfd.promise();
}

fooA()
.then(function() {
  return fooB();
})
.then(function() {
  return fooC();
})
.done(function() {
  console.log('All success');
})
.fail(function () {
  console.log('Some one fail');
})


// outcome =>
// exec fooA
// fooA fail
// Some one fail