ajax-fun-for-zac.js

function sendDataToAmazon(dataToSend) {
  return getAmazonKey()
    .then(getUrlWithKey)
    .then(function(url) {
      /* Sometimes it's easier to inline if you have
         data passed into original function which is only
         needed in the middle of a promise chain*/
      return sendDataToUrl(url, dataToSend);
    })
    .then(updateUI);
}


function getAmazonKey() {
  return $.get('/amazon/keys').then(function(data) {
    return { key: data.key, ;
  }
}

function getUrlWithKey(key) {
   return $.get('/amazon/urls?key=' + key).then(function(data) {
     return data.url;
   }); 
  }
}

function sendDataToUrl(url, dataToSend) {
  return $.ajax({
    method: 'POST',
    url: url,
    data: dataToSend,
    encoding: 'whatever-files-types?'
  });
}

function updateUI(data) {
  $('#my-selector').html('It worked!'); 
}