function on()

in src/lib/eventify.js [25:33]

• 8 lines of code
• 2 McCabe index (conditional complexity)

    function on(eventName: string, callback: Function): void {
        let eventListeners = listeners.get(eventName);
        if (!eventListeners) {
            eventListeners = new Set();
            listeners.set(eventName, eventListeners);
        }

        eventListeners.add(callback);
    }