Change Border Color if Input TextBox value is null (empty) in jQuery

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" />
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript" src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/js/bootstrap.min.js"></script>
<script type="text/javascript">
    $(function () {
        $("#btnlogin").on("click", function () {
            var isValid;
            $(".input").each(function () {
                if ($.trim($(this).val()) == '') {
                    $(this).css('border-color', 'red');
                    isValid = false;
                    return isValid;
                } else {
                    $(this).css('border-color', '');
                    isValid = true;
                    return isValid;
                }
            });
            return isValid;
        });
    });
</script>
<div class="form-group first">
    <label for="logemail">
        Email</label>
    <input type="text" class="form-control input" id="logemail">
</div>
<div class="form-group last mb-3">
    <label for="logpasswordpassword">
        Password</label>
    <input type="password" class="form-control input" id="logpassword">
</div>
<div class="form-group">
    <input type="submit" id="btnlogin" value="Log In" class="btn btn-block btn-primary">
</div>