<script type="text/javascript">

              function sub(){

        if(document.form1.xingming.value=="") {

            alert("姓名不能为空！");

            form1.xingming.focus();

            return false;

        }

        if(document.form1.mail.value=="") {

            alert("请输入邮箱");

            form1.mail.focus();

            return false;

        }

        else{

            var reg = /^\w+([-+.]\w+)*@\w+([-.]\w+)*\.\w+([-.]\w+)*$/;

             if(!reg.test(document.form1.mail.value)){

                            alert("邮箱格式不正确！");

                            form1.mail.focus();

                            return false;

                        }

            }

        if(document.form1.liuyan.value=="") {

            alert("请输入留言标题");

            form1.liuyan.focus();

            return false;

        }

        if(document.form1.neirong.value=="") {

            alert("请输入留言内容");

            form1.neirong.focus();

            return false;

        }

                document.form1.action="/跳转地址";

                document.form1.submit();

              }

</script>

以下是界面                           
 <div class="letterMain">

                                <form action="/zykj_tl/wyzx.zykj" method="post" name="form1" id="form1">

                                    <table class="letterMainTable">

                                        <tr>

                                             <td width="90" height="40" align="center" bgcolor="f3f3f3">姓  名：</td>

                                            <td height="40" width="269" align="left"><input type="text" name="xingming" id="xingming" maxlength="10"/><span class="redFont" style="position:relative;*top:-4px;">*</span></td>

                                            <td width="90" height="40" align="center" bgcolor="f3f3f3">E-mail：</td>

                                            <td height="40" align="left"><input type="text" name="mail" id="mail" maxlength="40"/></td>

                                        </tr>

                                        <tr>

                                            <td height="40" align="center" bgcolor="f3f3f3">地址：</td>

                                            <td height="40" align="left"><input type="text" name="dizhi" id="dizhi" maxlength="50"/></td>

                                            <td height="40" align="center" bgcolor="f3f3f3">QQ号码:</td>

                                            <td height="40" align="left"><input type="text" name="qq" id="qq" maxlength="20"/></td>

                                        </tr>

                                        <tr>

                                            <td height="40" align="center" bgcolor="f3f3f3">留言主题：</td>

                                            <td height="40" align="left" colspan="3"><input type="text" style="width:551px;" name="liuyan" id="liuyan" maxlength="50"/><span class="redFont" style="position:relative;*top:-4px;">*</span></td>

                                        </tr>

                                        <tr>

                                            <td height="178" align="center" bgcolor="f3f3f3">内  容</td>

                                            <td height="178" align="left" colspan="3"><textarea style="width:551px;height:160px;" name="neirong" id="neirong"></textarea><span class="redFont" style="position:relative;top:-67px;*top:-71px;">*</span></td>

                                        </tr>

                                    </table>

                                    <tr>

                                        <td height="70" align="center" colspan="4">

                                            <!-- <a href="###" class="surveySubmit" style="margin-left:226px;">提 交</a>

                                                 <a href="###" class="surveyView">重 置</a> -->

                                            <input type="button" name="button" class="surveySubmit" onclick="sub()" style="margin-left:226px;margin-top:30px;" value="提交" style="border:0px;">

                                            <input type="button" name="button" class="surveyView" style="margin-top:30px" onclick="reset()" value="重置" style="border:0px;" >

                                        </td>

                                    </tr>

                                </form>

                            </div>