<form action="" class="frm" id="frm">
   <textarea name="content" id="content" minlength="10" maxlength="100"></textarea>
   <button type="submit" class="submit">提交</button>
</form>
<script src="http://code.jquery.com/jquery-2.1.4.min.js"></script>
<script src="http://ueditor.baidu.com/ueditor/ueditor.config.js"></script>
<script src="http://ueditor.baidu.com/ueditor/ueditor.all.js"></script>
<script>
$(function() {
  var editor = UE.getEditor('content');
  var $frm = $('#frm');
  $(".submit").click(function () {
      editor.sync();
      var content = editor.getContent(); 
      if (content == '') {
          alert("内容不能为空");
          return false;
      }
      $("#frm").submit();
  }); 
  // 编辑器内容变化时同步
  editor.addListener('contentChange', function() {
      editor.sync();
      $('#content').trigger('change');
  });
});
</script>