gistfile1.js

    this.post('#/reply', function (context) {
      var fields = this.params, doc = {};
      doc.content = fields['post'];
      doc.datetime = new Date.now();
      doc.thread_id = fields['thread_id'];
      doc.type = 'post';
      doc.user_id = 'chapel';
      console.log(doc);
      db.saveDoc(doc, {
        success: function() {
          this.redirect('#/thread/'+fields.thread_id);
        },
        error: function() {
          alert('Error saving document.');
          this.redirect('#/thread/'+fields.thread_id);
        }
      });
      return false;
    });

gistfile2.html

<div id="reply">
  <form action="#/reply" method="POST">
    <input type="hidden" name="thread_id" value="" />
    <textarea name="post" cols=100 rows=10></textarea>
    <p><input type="submit" value="Reply" /></p>
  </form>
</div>