nk20/note_kfet/static/js/konami.js

/*
 * Konami code support
 */

// Cursor denote the position in konami code
let cursor = 0
const KONAMI_CODE = [38, 38, 40, 40, 37, 39, 37, 39, 66, 65]

function afterKonami() {
    // Load Rythm.js
    var rythmScript = document.createElement('script')
    rythmScript.setAttribute('src','//unpkg.com/rythm.js@2.2.5/rythm.min.js')
    document.head.appendChild(rythmScript)

    rythmScript.addEventListener('load', function() {
        // Ker-Lyon audio courtesy of @adalan, ker-lyon.fr
        const audioElement = new Audio('/static/song/konami.ogg')
        audioElement.loop = true
        audioElement.play()

        const rythm = new Rythm()
        rythm.connectExternalAudioElement(audioElement)
        rythm.addRythm('card', 'pulse', 50, 50, {
            min: 1,
            max: 1.1
        })
        rythm.addRythm('d-flex', 'color', 50, 50, {
           from: [64,64,64],
           to:[128,64,128]
        })
        rythm.addRythm('nav-link', 'jump', 150, 50, {
              min: 0,
              max: 10
        })
        rythm.start()
    });
}

// Register custom event
document.addEventListener('keydown', (e) => {
    cursor = (e.keyCode == KONAMI_CODE[cursor]) ? cursor + 1 : 0;
    if (cursor == KONAMI_CODE.length) {
        afterKonami()
    }
});