misuzu-interim/assets/misuzu.js/events/events.js

const MszSeasonalEvents = function() {
    const events = [];

    return {
        add: eventInfo => {
            if(!events.includes(eventInfo))
                events.push(eventInfo);
        },
        dispatch: () => {
            for(const info of events)
                if(info.isActive())
                    info.dispatch();
        },
    };
};