demo.js

var files = [
  'javascript/foo.js',
  'css/bar.css',
  'images/hello.png',
  'images/world.jpg'
];

var fileSends = files.map(function (filePath) {
  //Loops over files, passing in file[index] as filePath
  //It returns a new array based on whatever is returned from each function call
  return filesystem.loadFileByPath(filePath) //loads the file off the hard-disk and returns it
})
.map(function (actualFile) {
  //So now we have an array of loaded files, which we map again
  return amazon.uploadToCDN(actualFile)
});