iz/lib/utils/luhnCheck.js

Validation for node and the web.

"use strict";

/**
 * @author Phil Green (ShirtlessKirk) https://gist.github.com/2134376
 */
module.exports = function luhnChk(luhn) {
  var len = luhn.length,
      mul = 0,
      prodArr = [[0, 1, 2, 3, 4, 5, 6, 7, 8, 9], [0, 2, 4, 6, 8, 1, 3, 5, 7, 9]],
      sum = 0;

  while (len--) {
    sum += prodArr[mul][parseInt(luhn.charAt(len), 10)];
    mul ^= 1;
  }

  return sum % 10 === 0 && sum > 0;
};