Calculate EAN & UPC-A check digit using the Javascript step

Abstract: Neither the Add a checksum nor the Data Validator step provide calculation or check for EAN / UPC checkdigit.
Authors: Ludwig Weiss
License: LGPL
Kettle version: Kettle 3.2.5 and up (and maybe also a bit down?)

1. In a Javascript step create a new Script page and mark it as Start script
2. paste the following code into this page

   // String reverse
   String.prototype.reverse =
   function()
   {
   	splitext = this.split("");
   	revertext = splitext.reverse();
   	reversed = revertext.join("");
   	return reversed;
   }
   
   // function to calculate EAN / UPC checkdigit
   function eanCheckDigit(s)
   {
   	var result = 0;
   	var rs = s.reverse();
   	for (counter = 0; counter < rs.length; counter++)
   	{
   		result = result + parseInt(rs.charAt(counter)) * Math.pow(3, ((counter+1) % 2));
   	}
   	return (10 - (result % 10)) % 10;
   }
   

3. use the function in the transform script like

   var cd = eanCheckDigit(sUPC);