Javascript credit card validator using Luhn's Algorithm

luhns.js

function isValidCreditCard(number) {

  var len = number.length,
      multiply = 1,
      sum = 0,
      val;

  while (len--) {
    val = parseInt(number.charAt(len), 10);
    sum += (multiply ^= 1) ? Math.trunc(val * 2 / 10) + (val * 2 % 10) : val;
  }

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

https://jsfiddle.net/ccwz1q4s/

~4.3 million ops/sec - http://jsperf.com/cc-validator