gistfile1.txt

function isCreditCard( CC ) {
     if (CC.length > 19)
          return (false);

     sum = 0; multiplier = 1; l = CC.length;
     
     for (i = 0; i < l; i++)
     {
     	digit_to_process = getCharAtIndexFromEndOfString(CC,i);
     	tmp_product = parseInt(digit_to_process) * multiplier;
        sum += getProduct(tmp_product);
        multiplier = flip(multiplier);
     }
     return sum % 10 == 0;
}
function getProduct(number){
	return number >=10 ? (tproduct % 10) + 1 : number;
}
function flip(num){
	return num == 1 ? 2 : 1;
}
function getCharAtIndexFromEndOfString(ccstring,index,length){
	ccstring.substring(ccstring.length-index-1,ccstring.length-index);
}