Javascript - Form validation

<!DOCTYPE html>
<html>
<head>
    <title></title>
</head>
<body>
<form name="ivandroForm">
    Username:  <input type="text" name="username" />
    Password:  <input type="password" name="password" />
    <input type="checkbox" name="checkBoxIsMale">
    <input type="submit" value="Verify" onclick="validator()" />
</form>

<script type="text/javascript">
    function validator(){
        if(ivandroForm.checkBoxIsMale.checked)
        {
            alert("You are male!");
        }
        else
        {
            alert("You are female!");
        }
    }
</script>
</body>
</html>