product.tpl

{if !empty($product->ean13)}<p>{l s='EAN:'} {$product->ean13}</p>{/if}

{addJsDef productEan13=$product->ean13|escape:'html':'UTF-8'}

product.js

function addCombination(idCombination, arrayOfIdAttributes, quantity, price, ecotax, id_image, reference, unit_price, minimal_quantity, available_date, combination_specific_price, ean13)

combination['ean13'] = ean13;

if (selectedCombination['ean13'] || productEan13)
    {
        if (selectedCombination['ean13'])
            $('#product_ean13 span').text(selectedCombination['ean13']);
        else if (productEan13)
            $('#product_ean13 span').text(productEan13);
            $('#product_ean13:hidden').show('slow');
    }
    else
        $('#product_ean13:visible').hide('slow');

combinationsJS[k]['ean13'] = combinations[i]['ean13'];