JavaWeb-前端获取ckeditor的textarea的值

前端获取ckeditor的值：

HTML：

<div class="form-group">
	<label for="description" class="col-sm-2 control-label">描述:</label>
	<div class="col-sm-9 col-md-9">
		<textarea th:field="*{description}" class="form-control" rows="15" id="description" name="description" htmlEscape="false" placeholder="请输入200~2000个字符" required></textarea>
	</div>
</div>

JS：

<script type="text/javascript">
    window.onload = function()
    {
        CKEDITOR.replace( 'description');
    };
</script>

<script type="text/javascript">        
        function checkForm() {
        //description对应的ID值
	var topicContent=CKEDITOR.instances.description.document.getBody().getText(); 
    	if (topicContent =="")  
    	{  
    		layer.msg("请填写描述！");
            return false;  
    	}   
    	if (topicContent.length<500)  
    	{  
    		layer.msg("描述必须是500字以上！");
            return false;  
        }
	}
</script>