err = 0;
errc = ['OK'];
errc[1] = 'Please verify the zip code (5 or 9 digits).';
errc[2] = 'Please enter the telephone number, including area code.';
errc[3] = 'Please check the expiration date: four digits, '
+ 'e.g., 0709 is the correct date for July, 2009.';
errc[4] = 'This card is not working; can you check the card number again?';
errc[5] = 'Please do not leave this field blank.';
errc[6] = 'Please fill in the email address.';
errc[7] = 'Please check the expiration date: apparently it is expired.';
errc[8] = 'Please check the expiration date: it is not valid.';
errc[9] = 'Please complete the entry.';
errc[10] = 'Please enter a numerical value (may include an exponent e+N).';
errc[11] = 'Please enter a complete URL.';


function nwts(s) { // no white space
    return s.replace(/\s+/g, '');
}

function trimwts(s) { // trim white space
    return s.replace(/^\s+|\s+$/g, '');
}

function number(s) { // any number, including exponent
    //s = nwts(s) - 0;
    var temp = isNaN(s);
    err = isNaN(s) || s=='' ? 10 : 0;
    return [err ? 0 : s];
}

function zip(s) { // zip code
    var a = nwts(s).match(/\d{5}(-?\d{4}){0,1}/g);
    err = a != null && a.length ? 0 : 1;
    return a;
}

function tel(s) { // telephone, with area code + opt prefixes
    var a = s.replace(/\D+/g, '-');
    a = a.match(/(\d+-?)*(\d{3}-?){2}\d{4}/g);
    err = a != null && a.length ? 0 : 2;
    return a;
}

/* this code is copied from
http://www.codelib.net/home/jkm/checksum.js */

function checksum(s) { // thanks to daniel amor for AMEX specs
    var p = 0, e = 8, t = 0, c = [], r = 0, l = 0, i;
    if (s.length != 16) {
        t = 1;
        e = s.length == 13 && 6 || s.length == 15 && 7;
    }
    for (i = p; i < e; i++)
        r += (c[i] = s.charAt(i * 2 + t) * 2) > 9
  ? Math.floor(c[i] / 10 + c[i] % 10)
  : c[i];
    for (i = p; i < e + t; i++) l += s.charAt(i * 2 + 1 - t) - 0;
    l += r;
    return e && l % 10 == 0;
}

function cardno(s) {
    s = s.replace(/\D+/g, '');
    err = checksum(s) ? 0 : 4;
    return [s];
}

function text(s) {
    s = trimwts(s);
    err = s.length ? 0 : 5;
    return [s];
}

function words(s) {
    s = trimwts(s);
    err = /\s/.test(s) ? 0 : 9;
    return [s];
}

function email(s) {
    a = s.match(/\S+@([-\w]+\.)+\w+/g);
    err = a != null && a.length ? 0 : 6; //
    return a;    
}

function url(s.html) {
    a = s.match(/\w{2,}:\/{2}([-\w]+\.)+\w+\S*/g);
    err = a != null && a.length ? 0 : 11;
    return a;
}

function expires(s) {
    s = nwts(s);
    var m = new Date()
    var m_year = m.getFullYear() % 100, m_month = m.getMonth();
    if (s.length != 4 || isNaN(s))
        err = 3;
    else {
        s_month = s.substring(0, 2) - 0;
        s_year = s.substring(2, 4) - 0;
        if (m_year > 70 && s_year < 30) s_year += 100;
        /* "Let your great grandson worry about that." */
        if (s_year < m_year || s_year > m_year + 7) err = 8;
        else if (s_year == m_year && !(s_month > m_month)) err = 7;
        else err = 0;
    }
    return [s];
}

function valid(element, check) {
    if (element.type == 'text' || element.type == 'textarea' || element.type == 'password') {
        return check(element.value);
    } else return check(element);
}

present_element = null, present_error = null;

function validate(cDiv, list) {
    var errmsg = '';
    var flag = 0;
    $(cDiv).find(':input').each(function() {
        var element = this;
        var n = this.id, out;
        if (list[n] && list[n].verify) {
            out = valid(element, list[n].verify);
            if (err && (list[n].force || list[n].err != err)) {
                list[n].err = err;
                present_error = err;
                present_element = element;
                errmsg += list[n].message + '\n';
                flag = 1;
            }
            else if (!err && list[n].filter) {
                element.value = out.join(', ');
            }
        }
    });
    if (flag == 0) {return true;}
    else {alert(errmsg);  return false;}
}