waldo.html.erb

<% if logged_in? -%>
<script type="text/javascript">
function wheresWaldo(users) {
  document.write("<p>Users on this page: ")
  var links = []
  users.forEach(function(user) {
    var pieces = user.split('/')
    links.push('<a href="/users/' + pieces[0] + '">' + pieces[1] +  '</a>')
  })
  document.write(links.join(", ") + "</p>")
}
</script>
<script type="text/javascript" src="http://localhost:3456/track_and_list?callback=wheresWaldo&amp;name=<%= URI.escape("#{current_user.id}/#{current_user.name.split(" ").first}") %>&amp;location=<%= URI.escape(request.request_uri) %>"></script>
<% end -%>