title: jQuery $(this) problems with $.post()
body: <p>So here's my code for when a user clicks a follow button:</p>
  
  <pre><code>$('.follow_btn').click(function() {
      $(this).html('&lt;img src = "../assets/style_images/loading.gif"&gt;');
      var userId = $(this).attr('id');
      $.post('../assets/scripts/ajax_follow_parse.php', {
          userId: userId
      }, function(data) {
          $(this).html(data);
      });
  });
  </code></pre>
  
  <p>It is quite happy to replace it with the loading gif as shown on line 2. But when it returns the data and replace it with the data returned on line 4.</p>
  
  <p>How can I fix this?</p>