function isEmailAddr(email) {
    var result = false
    var theStr = new String(email)
    var index = theStr.indexOf("@");
            
    if (index > 0) {
        var pindex = theStr.indexOf(".",index);
        if ((pindex > index+1) && (theStr.length > pindex+1))
        result = true;
    }
    return result;
}
        
function validateData() {
    var check =  this.document.feedback;
    var invalid = " "; // Invalid character is a space
    var minLength = 4; // Minimum length
    var email =check.email.value;
            
    if (check.name.value == '') {
        alert ("Please enter your name.");
        check.name.focus();
        return (false);
    }
            
    if (!isEmailAddr(email)){
        alert("Please enter a complete email address in the form: yourname@yourdomain.com");
        check.email.focus();
        return (false);
    }
            
    if (check.comments.value == '') {
        alert ("Please enter your comments.");
        check.comments.focus();
        return (false);
    }
            
    check.submit();
}