Untitled

<!DOCTYPE html>
<html lang="es" dir="ltr">
    <head>
        <meta charset="utf-8">
        <title>Validación de formulario</title>
        <script type="text/javascript">
            const name_is_valid = (name) => {
                var len = name.length;
                if ((len >= 2) && (name.charAt(0) !== ' ') && (name.charAt(len-1) !== ' ')) {
                    return true;
                }
                return false;
            }

            const age_is_valid = (age) => {
                var casted = Number(age)
                if (age > 0) {
                    return true;
                }
                return false;
            }

            const mail_is_valid = (mail) => {
                if (mail.includes('@')) {
                    return true;
                }
                return false;
            }

            const submit_if_valid = () => {
                var name = document.getElementaByName('name')[0];
                var age = document.getElementaByName('age')[0];
                var mail = document.getElementaByName('mail')[0];
                var form = document.getElementaByTagName('form')[0];

                if (name_is_valid(name) && age_is_valid(age) && mail_is_valid(mail)){
                    form.submit();
                }
            }
        </script>
    </head>
    <body>
        <form action="index.html" method="post" onsubmit="submit_if_valid()">
            Nombre: <input type="text" name="name"> <br>
            Edad: <input type="text" name="age"> <br>
            E-mail: <input type="text" name="mail"> <br>
            <input type="submit" name="" value="Enviar consulta">
        </form>
    </body>
</html>