Observable Map

observable-map.js

export default class ObservableMap extends Map {
  constructor(...args) {
    super(...args)
    this._onSet = new Set()
    this._onDelete = new Set()
    this._onClear = new Set()
  }
  
  onSet(f) {
    this._onSet.add(f)
    return this
  }
  
  offSet(f) {
    this._onSet.delete(f)
    return this
  }
  
  onDelete(f) {
    this._onDelete.add(f)
    return this
  }
  
  offDelete(f) {
    this._onDelete.delete(f)
    return this
  }
  
  onClear(f) {
    this._onClear.add(f)
    return this
  }
  
  offClear(f) {
    this._onClear.delete(f)
    return this
  }
  
  set(key, value) {
    super.set(key, value)
    this._onSet.forEach(f => f(key, value))
    return this
  }
  
  delete(key) {
    super.delete(key)
    this._onDelete.forEach(f => f(key))
    return this
  }
  
  clear() {
    super.clear()
    this._onClear.forEach(f => f())
    return this
  }
}