Method dispatchEvent

core/util/eventtarget.js:27–34

(event)

    }

    dispatchEvent(event) {
        if (!this._listeners.has(event.type)) {
            return true;
        }
        this._listeners.get(event.type)
            .forEach(callback => callback.call(this, event));
        return !event.defaultPrevented;
    }
}