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April 4, 2017 02:54
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Event Emitter implementation in typescript
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| declare const _ | |
| export class EventEmitter { | |
| _listeners: {[key: string]: Function[]} = {} | |
| _eventQueue: {[key: string]: any[]} = {} | |
| on(eventName, listener: Function) { | |
| this._listeners[eventName] = this._listeners[eventName] || [] | |
| this._listeners[eventName].push(listener) | |
| this._callPendingEvents(eventName) | |
| return listener | |
| } | |
| once(eventName, listener: Function) { | |
| this._listeners[eventName] = this._listeners[eventName] || [] | |
| const listenerWrapper = (data)=> { | |
| listener(data) | |
| this.remove(eventName, listenerWrapper) | |
| } | |
| this._listeners[eventName].push(listenerWrapper) | |
| this._callPendingEvents(eventName) | |
| return listener | |
| } | |
| emit(eventName: string, ...data) { | |
| this._callListeners(eventName, ...data) | |
| return this | |
| } | |
| queueEvent(eventName: string, ...data){ | |
| if(this._listeners && this._listeners[eventName]){ | |
| this._callListeners(eventName, ...data) | |
| } | |
| else { | |
| this._eventQueue[eventName] = data | |
| } | |
| } | |
| _callPendingEvents(event): void { | |
| if (this._eventQueue.hasOwnProperty(event)) { | |
| const data = this._eventQueue[event] | |
| this._callListeners(event, ...data) | |
| delete this._eventQueue[event] | |
| } | |
| } | |
| _callListeners(event, ...data): void { | |
| _.each(this._listeners[event], (handler)=> { | |
| _.defer(()=> handler(...data) ) | |
| }) | |
| } | |
| remove(eventName?: string, listener?: Function) { | |
| if(!eventName){ | |
| this._listeners = {} | |
| this._eventQueue = {} | |
| } | |
| else if(this._listeners[eventName]){ | |
| if(listener){ | |
| const removedListenersCount = this._listeners[eventName].length | |
| this._listeners[eventName] = null | |
| return removedListenersCount | |
| } | |
| else { | |
| const listenerIndex = _.findIndex(this._listeners[eventName], (listenerToCompare)=> | |
| listener === listenerToCompare | |
| ) | |
| const removed = _.pullAt(this._listeners[eventName], listenerIndex) | |
| return removed.length | |
| } | |
| } | |
| } | |
| } |
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