class Subscribable { constructor() { this.events = { addSelf: [], editSelf: [], removeSelf: [], changeSelf: [] } this.eventDeps = { addSelf: ["changeSelf"], editSelf: ["changeSelf"], removeSelf: ["changeSelf"], changeSelf: [] } } subscribe(event, callback) { if (this.events[event]) { this.events[event].push(callback) } else { throw new Error(`Cannot subscribe to non-existent event ${event}, available events are: ${Object.keys(this.events).join(", ")}`) } } unsubscribe(event, callback) { const index = this.events[event].indexOf(callback) if (index === -1) throw new Error(`Tried to remove a nonexisting subscription from event ${event}`) this.events[event].splice(index, 1) } broadcast(event, data) { this.eventDeps[event].concat(event).forEach(eventName => { this.events[eventName].forEach(f => f(event, data)) }) } } export {Subscribable}