title: JS Request getting called twice in a row
body: <p>I'm working on the Ruby on Rails Tutorial. I have the asynchronous follow buttons working. Interestingly, each of the javascript calls is getting called twice in a row when I click the button. Any thoughts on how I make it only send one request? Here is my log</p>
  
  <pre><code>Started POST "/tag_user_relationships/123" for
  127.0.0.1 at 2011-06-13 21:18:59 -0700   Processing by TagUserRelationshipsController#destroy as JS   Parameters: {"utf8"=&gt;"✓", "authenticity_token"=&gt;"goedvibRxKtDRiAufp1ThWJP0rRBU2cMH2xp7qodKws=", "commit"=&gt;"Unfollow", "id"=&gt;"123"}   User Load (0.2ms)  SELECT `users`.* FROM `users` WHERE `users`.`id` = 2 LIMIT 1   TagUserRelationship Load (0.2ms)  SELECT `tag_user_relationships`.* FROM `tag_user_relationships` WHERE `tag_user_relationships`.`id` = 123 LIMIT 1   Tag Load (0.2ms)  SELECT `tags`.* FROM `tags` WHERE `tags`.`id`
  = 9 LIMIT 1   TagUserRelationship Load (0.3ms)  SELECT `tag_user_relationships`.* FROM `tag_user_relationships` WHERE `tag_user_relationships`.`tag_id` = 9 AND (`tag_user_relationships`.user_id
  = 2) LIMIT 1   SQL (0.1ms)  BEGIN   AREL (0.2ms)  DELETE FROM `tag_user_relationships` WHERE `tag_user_relationships`.`id` = 123   SQL (0.4ms)  COMMIT   SQL (0.4ms)  SELECT COUNT(*) FROM `users` INNER JOIN `tag_user_relationships` ON `users`.id = `tag_user_relationships`.user_id WHERE ((`tag_user_relationships`.tag_id = 9))   SQL (0.3ms)  SELECT COUNT(*) FROM `tags` INNER JOIN `tag_user_relationships` ON `tags`.id
  = `tag_user_relationships`.tag_id WHERE ((`tag_user_relationships`.user_id = 2)) Rendered tag_user_relationships/_form.js.erb (15.8ms) Rendered tags/_follow.html.erb (2.1ms) Rendered tag_user_relationships/destroy.js.erb (20.3ms) Completed 200 OK in 138ms (Views: 28.1ms | ActiveRecord: 2.3ms)
  
  
  Started POST "/tag_user_relationships/123" for
  127.0.0.1 at 2011-06-13 21:18:59 -0700   Processing by TagUserRelationshipsController#destroy as JS   Parameters: {"utf8"=&gt;"✓", "authenticity_token"=&gt;"goedvibRxKtDRiAufp1ThWJP0rRBU2cMH2xp7qodKws=", "id"=&gt;"123"}   User Load (0.2ms)  SELECT `users`.* FROM `users` WHERE `users`.`id` = 2 LIMIT 1   TagUserRelationship Load (0.2ms)  SELECT `tag_user_relationships`.* FROM `tag_user_relationships` WHERE `tag_user_relationships`.`id` = 123 LIMIT 1 Completed 404 Not Found in 70ms
  
  ActiveRecord::RecordNotFound (Couldn't find TagUserRelationship with ID=123): app/controllers/tag_user_relationships_controller.rb:14:in `destroy'
  
  Rendered /Users/me/.rvm/gems/ruby-1.9.2-p136@rails3tutorial/gems/actionpack-3.0.8/lib/action_dispatch/middleware/templates/rescues/_trace.erb (1.0ms) Rendered /Users/me/.rvm/gems/ruby-1.9.2-p136@rails3tutorial/gems/actionpack-3.0.8/lib/action_dispatch/middleware/templates/rescues/_request_and_response.erb (153.6ms) Rendered /Users/me/.rvm/gems/ruby-1.9.2-p136@rails3tutorial/gems/actionpack-3.0.8/lib/action_dispatch/middleware/templates/rescues/diagnostics.erb within rescues/layout (160.2ms)
  </code></pre>
  
  <p>And here is my view</p>
  
  <pre><code>$("#&lt;%= "follower_info#{@tag.id}" %&gt;").html("&lt;%=escape_javascript(pluralize(@tag.followers.count,'follower'))%&gt;");     
  var link = $('&lt;a&gt;').attr('href',"&lt;%=user_tags_path(current_user) %&gt;").text("&lt;%= escape_javascript(pluralize(current_user.beats.count,'tag')) %&gt;");
  $("#&lt;%= "user#{current_user.id}_following" %&gt;").html(link); $("#&lt;%= "follow_form#{@tag.id}" %&gt;").html("&lt;%= escape_javascript("#{render('tags/unfollow', :tag =&gt; @tag)}").html_safe %&gt;");
  </code></pre>
  
  <p>And my controller</p>
  
  <pre><code>  def create
      @tag = Tag.find(params[:tag_user_relationship][:tag_id])
      current_user.follow_tag!(@tag)
      respond_to do |format|
        format.html { redirect_to @tag }
        format.js
      end   
    end
  </code></pre>