JavaScript 最佳表单验证

<html>
    <head>
        <meta http-equiv="Content-Type" content="text/html; charset=gb2312">
        <title>注册会员</title>
        <style type="text/css">
            .table {
                border-collapse:collapse;
                font-size:12px;
            }
            .input {
                width:200px;
                height:22px;
            }
            .stats1 {
                color:#aaa;
            }
            .stats2 {
                color:#000;
            }
            .stats3 {
                color:red;
            }
            .stats4 {
                color:green;
            }
        </style>
    </head>
    <body>
        <form action="index.php" method="post" onSubmit="return regCheck('click')">
        <table border="0" align="center" width="500" class="table">
            <tr>
                <td width="80" height="25" align="right">用户名称：</td><td><input type="text" name="username" value="" class="input" /> <span class="stats1"></span></td>
            </tr>
            <tr>
                <td width="80" height="25" align="right">密码：</td><td><input type="password" name="password" value="" class="input" /> <span class="stats1"></span></td>
            </tr>
            <tr>
                <td width="80" height="25" align="right">确认密码：</td><td><input type="password" name="repass" value="" class="input" /> <span class="stats1"></span></td>
            </tr>
            <tr>
                <td width="80" height="25" align="right">电子邮箱：</td><td><input type="text" name="email" value="" class="input" /> <span class="stats1"></span></td>
            </tr>
            <tr>
                <td height="30"></td><td align="left"><input type="submit" name="send" value="提交" /> <input type="reset" value="重置" /></td>
            </tr>
        </table>
        </form>
    </body>
</html>
<script language="javascript">
// 找到 input 后面的 SPAN 标签
function gspan(cobj){
    while(true){
        if(cobj.nextSibling.nodeName!="SPAN")
            cobj=cobj.nextSibling;
        else
            return cobj.nextSibling;
    }
}

function check(obj, info, fun, click){
    var sp=gspan(obj);
    obj.onfocus=function(){
        sp.innerHTML=info;
        sp.className="stats2";

    }

    obj.onblur=function(){
        if(fun(this.value)){
            sp.innerHTML="输入正确√";
            sp.className="stats4";

        }else{
            sp.innerHTML=info;
            sp.className="stats3";
        }
    }

    if(click=="click")
&nbs

补充：web前端 , JavaScript ,