Vigenère-Chiffre

vigenere.js

/*
 * source: https://rosettacode.org/wiki/Vigen%C3%A8re_cipher#JavaScript
 */

// vigenere
function vigenere(text, key, decode) {
    // helper
    const ordA = a => a.charCodeAt(0) - 65;
    // main
    let i = 0, b;
    key = key.toUpperCase().replace(/[^A-Z]/g, '');
    return text.toUpperCase().replace(/[^A-Z]/g, '').replace(/[A-Z]/g, function (a) {
        b = key[i++ % key.length];
        return String.fromCharCode(((ordA(a) + (decode ? 26 - ordA(b) : ordA(b))) % 26 + 65));
    });
}