JS Class __proto__ Proxy

conter.js

function sortAscending ([ k1, v1 ], [ k2, v2 ]) {
  if (v1 < v2) {
    return -1
  }
  if (v1 > v2) {
    return 1
  }
  return 0
}

function sortDescending ([ k1, v1 ], [ k2, v2 ]) {
  if (v1 < v2) {
    return 1
  }
  if (v1 > v2) {
    return -1
  }
  return 0
}

module.exports = class Counter {
  constructor () {
    this.values = {}
    // let self = this
    this.entries = function () {
      return Object.entries(this.values)
    }

    this.sortedEntries = function (decreasing = false) {
      let e = Array.from(this.entries())
      if (decreasing) {
        e.sort(sortDescending)
      } else {
        e.sort(sortAscending)
      }
      return e[ Symbol.iterator ]()
    }

    this[ Symbol.iterator ] = function * () {
      yield * Object.entries(this.values)
    }

    this.sorted = function (compare = sortAscending) {
      let e = Array.from(this.entries())
      e.sort(compare)
      return e[ Symbol.iterator ]()
    }

    this.__proto__ = new Proxy(this.values, {
      set (me, key, value) {
        if (typeof value !== 'number') {
          throw new TypeError(`the value of ${key} was ${typeof value}, expected number`)
        }
        me[ key ] = value
        return true
      },
      get (me, key) {
        let v = me[ key ]
        if (v === undefined || v === null) {
          me[ key ] = 0
        }
        return me[ key ]
      },
      has (me, prop) {
        return prop in me
      },
      ownKeys (me) {
        return Reflect.keys(me)
      },
      getOwnPropertyDescriptor (target, prop) {
        return Reflect.getOwnPropertyDescriptor(target, prop)
      }
    })
  }