providerupdater.js

class ProviderUpdater {
  constructor (provider) {
    this._provider = provider

    this._handler = {
      get: (obj, name) => {
        return this._provider[name]
      },
      set: (obj, name, value) => {
        this._provider[name] = value
      }
    }
    this._proxy = new Proxy(this._provider, this._handler)
  }

  get provider () {
    return this._proxy
  }

  set provider (provider) {
    this._provider = provider
  }
}

const providerA = {}
const updater = new ProviderUpdater(providerA)

const provider = updater.provider

provider.a = 55
console.log(provider.a)

// update the provider
const providerB = {}
updater.provider = providerB

// a no longer exists
console.log(provider.a)

provider.b = 99
console.log(provider.b)