ajax.js

request.onload = function () {
  if (this.status >= 200 && this.status < 400) {
    var data = JSON.parse(this.response)

    data.photos.photo.map(function (photo) {
      var image = generateImageFromPhotoObject(photo)
      wrapper.appendChild(image)
    })
  } else {
    wrapper.innerHTML = 'We recieved an error from the Flickr API. Please try again later.'
  }
}