先导入JS
<script type="text/javascript" src="fckeditor/fckeditor.js"></script>

验证：
<script type="text/javascript">
//非空验证
        function checkZSForm(){
            if($V("rbTitle")==""){
             alert("请填写标题"); return false;
            }
            var rbContent = FCKeditorAPI.GetInstance("rbContent").GetXHTML(true);
            if(rbContent == null || rbContent == ""){
                alert("请输入内容"); return false;
                    }
                    document.forms[0].submit(); //不为空则提交表单
        }

 //fck内容重置     
        function reset(){
             setValue("rbTitle","");
             var editor = FCKeditorAPI.GetInstance("rbContent");
                         editor.EditorDocument.body.innerHTML="";
        }
    </script>



上面的rbContent你FCK的实例名即instanceName

页面中的表单是这样的：
<tr bgcolor="#ECF5FF">
                <td height="300" align="right" valign="middle">
                 <font color="#FF0000">*</font>内容：
                </td>
                <td colspan="2" valign="top">
                 <FCK:editor instanceName="rbContent" height="400">
                    <jsp:attribute name="value">
                 
                     </jsp:attribute>
                 </FCK:editor>
                </td>
             </tr>