Guessing game fun using sessions with Sinatra

session_fun.rb

require 'sinatra'
require 'haml'
require 'json'

enable :sessions

get '/' do
  session[:answer] = %w[A B C D].sample
  haml :index
end

get '/guess/:value' do
  content_type :json
  old_answer = session[:answer]
  session[:answer] = %w[A B C D].sample
  if params[:value] == old_answer
    { :message => 'Correct answer!' }.to_json
  else
    { :message => "Wrong answer! It was #{old_answer}!" }.to_json
  end
end

__END__

@@index
!!!
%html
  %head
    %title Session Fun!
    %script{ :type => 'text/javascript', :src => '//ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js' }
    :javascript
      $(document).ready(function(){
          $('li.guess').each(function(i, elem){
              var elem = $(elem);
              elem.click(function(){
                  console.log('/guess/' + elem.html());
                  $.get('/guess/' + elem.html(), function(result){
                      alert(result.message);
                  });
              });
          });
      });
    :css
      html, body {
          background: #CCCCCC;
      }

      .main {
          width: 200px;
          height: 200px;
          margin: 75px auto 0;
          padding: 20px;
          background: white;
          border: 1px solid #DDDDDD;
      }

      h2 {
          text-align: center;
      }

      ul {
          list-style-type: none;
      }

      li.guess {
          font-size: 20px;
          cursor: pointer;
          margin-bottom: 10px;
          color: #3300FF;
          text-decoration: underline;
      }
  %body
    .main
      %h2 Guess the letter!
      %ul
        %li.guess My guess is A!
        %li.guess I'll try B.
        %li.guess Maybe C?
        %li.guess It's gotta be D...