//checks for empty values for required fields
function validate_required(field, alerttxt){
    with (field) {
        if (value == null || value == "") {
            alert(alerttxt);
            return false;
        }
        else {
            return true;
        }
    }
}

function validate_email(field, alerttxt){
    with (field) {
        apos = value.indexOf("@");
        dotpos = value.lastIndexOf(".");
        if (apos < 1 || dotpos - apos < 2) {
            alert(alerttxt);
            return false;
        }
        else {
            return true;
        }
    }
}

function validate_form(thisform){
    with (thisform) {
        if (validate_required(name, "Please Enter your name.") == false) {
            name.focus();
            return false;
        }
        if (validate_required(email, "Please Enter your email address.") == false) {
            email.focus();
            return false;
        }
        if (validate_required(message, "Please Enter your message.") == false) {
            email.focus();
            return false;
        }
        if (validate_email(email, "Please Enter a valid email address.") == false) {
            email.focus();
            return false;
        }
    }
}