promises.js

getUserDetails(cookie, function(error, user) {
  if(error) {/* do something with error */}

  if(user.isADangerToThePublic) {
    console.log('error')
    return
  }

  getUsersName(user, function(error, name, dob) {
    if(error) {/* do something with error */}
    isItTheirBirthday(dob, function(isBirthday) {
    )}

    do
  })
})


function getUserDetails (cookie) {
  console.log('getUserDetails:', this)

  const helper = () => {
    console.log('this in helper:', this)
  }

  helper()
}

var myFunction = getUserDetails.bind('cheese')
myFunction()

function doStuff () {
  console.log('start')

  getUserDetails(cookie)
  .then((user) => {
    console.log(user)

    var sam

    if(user.isADangerToThePublic) {
      throw new Error('User is bad')
    }

    return getUsersName(user)
  })
  .then((name, dob) => {
    console.log(name, dob)

    return isItTheirBirthday(dob)
  })
  .then(function (isBirthday) {
    console.log('all done. Is it your birthday?' + isBirthday)
  })
  .catch(function(error) {
    console.error('It has all gone wrong!', error)
  })

  console.log('end')
}





























function getUserDetails(cookie, callback) {
  setTimeout(function () {
    // do some stuff with user
    var user = getUser(cookie)
    callback(user)
  }, 1000)
}

descibe('stuff', function () {
  it('should get user from server', function (done) {

    //arrange
    var cookie = 123

    //act
    var user = getUserDetails(cookie, function (user) {

      // assert
      expect(user.name).to.be('sam')
      done()
    }
  })
})