前端判断登陆页面输入是否符合要求

<script type&＃61;"text/Javascript" src&＃61;"js/login.js">script>

<script language&＃61;"Javascript">

    function rec(){          

        alert("欢迎登入家庭管理系统"); 

    }

script>

<h2>新成员&＃xff1a;<a href&＃61;"${pageContext.request.contextPath}/register">注册a>h2>

${pageContext.request.contextPath}

取得绝对路径

-->

<form name&＃61;"f1" id&＃61;"f1" action&＃61;"login" method&＃61;"post" onsubmit&＃61;"return check()">         

        <table border&＃61;"0" width&＃61;"250px" height&＃61;"150px">

            <tr>

                <td>账号:td>

                <td><input type&＃61;"text" name&＃61;"username" id&＃61;"username"/>td>

            tr>

            <tr>

                <td>密码:td>

                <td><input type&＃61;"password" name&＃61;"password" id&＃61;"password"/>

                td>

            tr>

            <tr >

                <td colspan&＃61;"2"><input type&＃61;"checkbox" name&＃61;"remPwd" id&＃61;"remPwd"/>记住密码td>

            tr>

            <tr>

                <td align&＃61;"right"><input type&＃61;"submit" onclick &＃61; "rec()"value&＃61;"登录"/> td>

                <td  align&＃61;"center"> <input type &＃61; "reset"   value &＃61; "重置" >td>

            tr>

            <tr>

                <td colspan&＃61;"2" align&＃61;"center" >

                    <jsp:useBean id&＃61;"time" type&＃61;"java.io.Serializable"  beanName&＃61;"java.util.Date"/>

                    <hr>登入时间&＃xff1a;<%&＃61;time %><hr>

                td>

            tr>

            <tr>

                <td colspan&＃61;"2" align&＃61;"center" class&＃61;"msg_error" id&＃61;"msg" >

                <div id &＃61; "msg">

                    ${msg}

                div>  

                td>

            tr>

        table>

    form>

注意:

<jsp:useBean id&＃61;"time" type&＃61;"java.io.Serializable"  beanName&＃61;"java.util.Date"/>

                    <hr>登入时间&＃xff1a;<%&＃61;time %><hr>

当前登入时间

login.js页面:

function check(){

    var msg&＃61;document.getElementById("msg");

    var e_username&＃61;document.getElementById("username");

    var e_password&＃61;document.getElementById("password");

    var username&＃61;e_username.value;

    var password&＃61;e_password.value;

    if(username&＃61;&＃61;null || username&＃61;&＃61;""){

        //账号不能为空

        msg.innerHTML&＃61;"账号不能为空";

        e_username.style.border&＃61;"solid 1px #f00";

        return false;

    }

    if(password&＃61;&＃61;null || password&＃61;&＃61;""){  

        msg.innerHTML&＃61;"密码不能为空";

        e_password.style.border&＃61;"solid 1px #f00";

        retur

n false;

    }

    if(username.length<3 || username.length>7){

        //账号长度不合法   

        msg.innerHTML&＃61;"账号长度不合法&＃xff08;3~7内&＃xff09;";

        e_username.style.border&＃61;"solid 1px #f00";

        return false;

    }

    if(password.length<2 || password.length>20){

        //密码长度不合法

        msg.innerHTML&＃61;"密码长度不合法&＃xff08;2~20内&＃xff09;";

        e_password.style.border&＃61;"solid 1px #f00";

        return false;

    }

    return true;

}