为什么会出现警告未定义属性值

源自：2-7 用户管理之添加用户

为什么会出现警告未定义属性值

为什么我写时候placeholder和required会出现警告未定义属性值啊,下面的的input也有,但运行有没有错

提问者：落于寒4180575 2016-12-06 10:58

个回答

慕粉3173334

2017-01-04 20:43:32

placeholder和required是H5支持的

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落于寒4180575

2016-12-06 11:04:52

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head>
   <meta http-equiv="Content-Type" content="text/html;charset=UTF-8" />
   <title>Document</title>
</head>
<body>
    <h2>添加用户</h2>
    <form action = "doAction.php?act = addUser" method = "post">
        <table border = "1" cellpadding = "0" cellspacing = "0" width = "80%" bgcolor = "#ABCDEF">
            <tr>
               <td>用户名</td>
               <td><input type="text" name="username" id="" placeholder='请输入合法用户名' required='required'/></td>
           </tr>
           <tr>
               <td>密码</td>
               <td><input type="password" name="password" id="" placeholder='请输入密码' required='required'/></td>
           </tr>
           <tr>
               <td>年龄</td>
               <td><input type="number" name="age" id="" min='1' max='125' placeholder='请输入合法年龄' required='required'/></td>
           </tr>
           <tr>
                 <td colspan = '2'><input type = "submit" value = "添加用户"/></td>
           </tr>
        </table>
    </form>
</body>
</html>
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