Example of badly written code - loading photos and making it grayed after click

ugly_code.coffee

$(document).ready ->
  photoHTML = (photo) =>
    "<li><a id='photo_#{photo.id}' href='#{photo.url}'><img src='#{photo.url}' alt='#{photo.alt}' /></a></li>"

  $.ajax
    url: '/photos'
    type: 'GET'
    contentType: 'application/json'
    onSuccess: (response) =>
      for photo in response.photos
        node = $(photoHTML(photo)).appendTo($("#photos-list"))

        node.on('click', (e) =>
          e.preventDefault()
          node.find('img').prop('src', photo.url + '.grayscaled.jpg')
        )
    onFailure: =>
      $("#photo-list").append("<li>Failed to fetch photos.</li>")