HTML + JS Mecegah inputan agar tidak kosong + reset.

<!DOCTYPE html>
<html>
<head>
    <title>HTML + JS Mecegah inputan agar tidak kosong + reset.</title>
    <!--
    *ini adalah komentar
    *JScript form input username
    *yg mencegah kekosongan form input
    -->
    <script type="text/javascript">
    function matami_input(form)

    { if (form.username.value==""){
      alert("username anda belum di isi");
      form.username.focus();
      return (false);
      }
        return (true);
      }
    </script>


</head>
<body>
<!-- *form input type username
     *yang akan mencegah kekosongan username

 -->
<form method="post" action="aksi.php" onsubmit="return matami_input(this)">
<p>Username: <input name="username" type="text"></p>
<p><input name="submit" type="submit" value="Submit">
<input type="reset" value="reset"></input></p>


</form>

 </form>

</body>
</html>