let hub = () => ({ hub: Object.create(null), emit(event, data) { (this.hub[event] || []).forEach((handler) => handler(data)); }, on(event, handler) { if (!this.hub[event]) this.hub[event] = []; this.hub[event].push(handler); }, off(event, handler) { const i = (this.hub[event] || []).findIndex((h) => h === handler); if (i > -1) this.hub[event].splice(i, 1); if (this.hub[event].length === 0) delete this.hub[event]; }, });