Convert Nintendo friend codes to plain old integers, for whatever reason you might want to do that anyway

fc2int.js

function fc2int(fc) {
    const codes = '0123456789ABCDEFGHJKLMNPQRSTUVWXY';
    fc = fc.toUpperCase().match(new RegExp(`[${codes}]`, 'g'));
    return -1 + fc
        .map((a, i) => (codes.indexOf(a) + 1) * Math.pow(codes.length - 1, i))
        .reduce((a, b) => a + b);
}