[Nexus]

LocoThatCould,

<form id="fr">
    <input type="text" id="username" />
    <input type="password" id="pass" />
    <input type="submit" />
</form>
<script>
    document.querySelector('#fr').addEventListener('submit', function(e) {
        if (!validate())
            e.preventDefault();
    });

    var userEmail = document.getElementById("username"),
        userPass = document.getElementById("pass"),
        regexp = new RegExp("^([a-z0-9_-]+\.)*[a-z0-9_-]+@[a-z0-9_-]+(\.[a-z0-9_-]+)*\.[a-z]{2,6}$"),
        regexpP = new RegExp("^[a-zA-Z0-9!@#$%^&*]{6,16}$");


    function validate() {
        var result = regexp.test(userEmail.value);
        if (!result) {
            userEmail.style.border = "2px solid red";
            alert('Некорректно введен Email!');
        } else
            userEmail.style.border = "2px solid green";


        if (!regexpP.test(userPass.value)) {
            result = false;
            userPass.style.border = "2px solid red";
            alert('Некорректно введен Пароль!')
        } else
            userPass.style.border = "2px solid green";


        return result;
    }
</script>