onsubmit="return check()"问题没反应

onsubmit="return check()"没有反应，提交表框直接到action="postreg.php页面上了，谁帮我解决一下！

<form action="postreg.php" method="post" onsubmit="return check()">
        <div class="user">
            <input type="text" name="username" placeholder="请输入用户名"><span></span>
        </div>
        <div class="mailbox">

            <input type="text" name="usermail" placeholder="请输入你的邮箱"><span></span>
        </div>
        <div class="pass">
            <input type="password" name="password" placeholder="请输入密码"><span></span>
        </div>
        <div class="pass">
            <input type="password" name="password2" placeholder="请再次输入密码"><span></span>
        </div>
        <div class="button">
            <button type="submit">立即注册<span></span></button>
        </div>
        <div class="register">
            <div class="registers"><a href="login.html" >返回登录</a></div>
            <div class="wjmm"><a href="wjmm.html" >忘记密码</a></div>
        </div>
        </form>


<script>
        function check(){
            let username = document.getElementsByName('usermane')[0].value.trim();
            let usermail = document.getElementsByName('usermail')[0].value.trim();
            let password = document.getElementsByName('password')[0].value.trim();
            
            let usernamereg = /^[a-zA-Z0-9]{3,10}$/;
        if(!usernamereg.test(username)) {
            alert('用户名必填.且只能大小定字符和数字构成.长度为3到10个字符.');
        return false;
        }
        
        }
        </script>

阅读 1.9k

<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> </head> <body> <form onsubmit="return check();" > <div class="user"> <input type="text" name="username" placeholder="请输入用户名"><span></span> </div> <div class="mailbox"> <input type="text" name="usermail" placeholder="请输入你的邮箱"><span></span> </div> <div class="pass"> <input type="password" name="password" placeholder="请输入密码"><span></span> </div> <div class="pass"> <input type="password" name="password2" placeholder="请再次输入密码"><span></span> </div> <button type="submit">立即注册<span></span></button> </form> <script> function check(){ let username = document.getElementsByName("username")[0].value.trim(); let usernamereg = /^[a-zA-Z0-9]{3,10}$/; if(!usernamereg.test(username)) { alert('用户名必填.且只能大小定字符和数字构成.长度为3到10个字符.'); return false } } </script> </body> </html>

onsubmit="return check()"问题没反应

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