Media Session. Next & Previous

index.js

// to add playlist action handlers
if (/* has playlist */) {
    window.navigator.mediasSession.setActionHandler('nexttrack', () => { /* your next item */ });
    window.navigator.mediasSession.setActionHandler('previoustrack', () => { /* your previous item */ });
}

// to cancel playlist action handlers
window.navigator.mediasSession.setActionHandler('nexttrack', null);
window.navigator.mediasSession.setActionHandler('previoustrack', null);