<script> function beforeSend(){ if(document.getElementById("password").value != document.getElementById("password1").value) return alert("请输入正确的密码"); } </script> <form method="post" action="/redister.html" onsubmit='beforeSend()'> <p><label for="loginName">登录名：</label><input name='loginName' type='text' pattern=".{3,20}">(3~20个字符)</p> <p><label for="password">登录密码：</label><input id='password' name='password' type='password' pattern=".{6,20}">(至少6位)</p> <p><label for="password1">重复密码：</label><input id='password1' name='password1' type='password' pattern=".{6,20}">(至少6位)</p> <p><label for="email">邮箱：</label><input name='email' type='email'>(请输入正确的邮箱地址)</p> <input type='reset' value='重置'><button type=submit>注册</button> </form>