bithook/src/ee.js

Payment lifecycle handler over bitcoind

let isFunction = function(obj) {
  return typeof obj == 'function' || false
}


export default class EventEmitter {
  constructor() {
    this.listeners = new Map()
  }

  on(label, callback) {
    this.listeners.has(label) || this.listeners.set(label, [])
    this.listeners.get(label).push(callback)
    return () => this.remove(label, callback)
  }

  remove(label, callback) {
    let listeners = this.listeners.get(label),
      index

    if (listeners && listeners.length) {
      index = listeners.reduce((i, listener, index) => {
        return (isFunction(listener) && listener === callback)
          ? i = index
          : i
      }, -1)
      
      if (index > -1) {
        listeners.splice(index, 1)
        this.listeners.set(label, listeners)
        return true
      }
    }
    return false
  }

  emit(label, ...args) {
    let listeners = this.listeners.get(label)
    
    if (listeners && listeners.length) {
      listeners.forEach((listener) => {
          listener(...args) 
      })
      return true
    }
    return false
  }
}