Js切换功能的简单方法

我估计很多正在学习css，js的朋友们也有这样的经历，刚在做这个js切换的时候，我想到了一个好的方法，马上给大家分享一下，希望你们能把它拿走

function changeDiv(index) 
{ 
for(var i=0;i<=5;i++) 
{ 
if(i == index) 
document.getElementById('dv_'+i).className="txt1"; 
else 
document.getElementById('dv_'+i).className="txt2"; 
} 
}

可样子大家可能看的不是很清楚，这样 吧，我把html也贴出来了，大家就看看吧，

<table width="100%" height="616" border="0" align="center" cellpadding="0" cellspacing="5" bgcolor="#FEFDF8" class="border1"> 
<tr> 
<td height="20" class="title2">会员注册</td> 
</tr> 
<tr> 
<td valign="top" bgcolor="#FEFDF8"> 
<table height="20"><tr><td></td></tr></table> 
<table width="100%" height="300" border="0" cellpadding="0" cellspacing="10"> 
<tr> 
<td width="100" align="right">会员名:</td> 
<td><asp:TextBox CssClass="txt" id="txt_name" onfocus="changeDiv(0)" onblur="cheaked();check_callback()" runat="server"/><div id="showState"></div></td> 
<td><div id="dv_0" class="txt2">5-20个字符(包括小写字母、数字、下划线、中文)</div></td> 
</tr> 
<tr> 
<td align="right">密码:</td> 
<td><asp:TextBox id="txt_pwd" TextMode="Password" CssClass="txt" onfocus="changeDiv(1)" runat="server"/></td> 
<td><div id="dv_1" class="txt2">请使用英文字母加数字或符号的组合密码</div></td> 
</tr> 
<tr> 
<td align="right">确认密码:</td> 
<td><asp:TextBox id="txt_pwd1" TextMode="Password" CssClass="txt" onfocus="changeDiv(2)" runat="server"/></td> 
<td><div id="dv_2" class="txt2">请重新输入密码</div></td> 
</tr> 
<tr> 
<td align="right">电子邮箱:</td> 
<td><asp:TextBox id="txt_mail" CssClass="txt" onfocus="changeDiv(3)" runat="server"/></td> 
<td><div id="dv_3" class="txt2">请输入常用电子邮箱</div></td> 
</tr> 
<tr> 
<td align="right">QQ/电话:</td> 
<td><asp:TextBox id="txt_tel" CssClass="txt" onfocus="changeDiv(4)" runat="server"/></td> 
<td><div id="dv_4" class="txt2">请填写您的QQ/电话号</div></td> 
</tr> 
<tr> 
<td align="right">验证码:</td> 
<td><asp:TextBox id="txt_vali" CssClass="txt" Width="150" onfocus="changeDiv(5)" runat="server"/><img id="vcodeimg" style="cursor:hand" src="tools/verifyimage.aspx" onClick="this.src= http://www.dftzc.com " title="点击刷新验证码" align="absmiddle" /><div id="showErro" runat=server></div></td> 
<td><div id="dv_5" class="txt2">请输入验证码</div></td> 
</tr> 
<tr> 
<td colspan="2" align="center"><INPUT type="checkbox" name="check_agreement"> 
<A href="#">我已阅读并同意会员条款</A></td> 
<td align="center" valign="bottom"><asp:Button runat="server" ID="btn_register" OnClick="btn_Register_Click" onclientclick="return vipRegister()" Text="会员注册"/></td> 
</tr> 
</table></td> 
</tr> 
</table>