Damm validation & generation code in PHP.Damm algorithm is a check digit algorithm that detects all single-digit errors and all adjacent transposition errors.

damm_check_digit.php

<?php
/**
 * The Damm check digit
 * For more information cf. http://en.wikipedia.org/wiki/Damm_algorithm
 * totally anti-symmetric quasigroup
 *
 * @author Wuri Nugrahadi <w.nugrahadi@gmail.com>
 */
if (! function_exists('taq'))
{
	function taq($digits)
	{
		$taq_table = array(
			'0317598642', '7092154863', '4206871359', '1750983426', '6123045978',
			'3674209581', '5869720134', '8945362017', '9438617205', '2581436790');
		$interim = 0;

		foreach (str_split($digits) as $digit) {
			if (! preg_match('~\d~', $digit))
			{
				return FALSE;
			}
			$interim = substr($taq_table[$interim], $digit, 1);
		}

		return $interim;
	}
}

if (! function_exists('calc_check_digit'))
{
	function calc_check_digit($digits)
	{		
		return $digits.taq($digits);
	}
}

if (! function_exists('is_check_digit_valid'))
{
	function is_check_digit_valid($digits)
	{
		return taq($digits) == 0;
	}
}

taq.js

function taq(digits)
{
	var taqTable = ['0317598642', '7092154863', '4206871359', '1750983426', '6123045978', '3674209581', '5869720134', '8945362017', '9438617205', '2581436790'];
	var interim = 0;
    var chars = digits.split('');
    var index, len;
      
    for (index = 0, len = chars.length; index < len; ++index) {
        var digit = parseInt(chars[index]);
        var taqRow = taqTable[interim];
        var strInterim = taqRow.substr(digit, 1);
        
        interim = parseInt(strInterim);
    }
      
    return interim;
}

console.log(taq('8436714657207786'));