Ads.js

const Client = function (data) {
  
  let copy = Object.keys(data);

  const
    reset = function () {
      copy = Object.keys(data);
    },

    nextIndex = function () {
      Math.floor(Math.random() * copy.length);
    },

    removeIndex = function (index) {
      copy.splice(index, 1);
      if (!copy.length) {
        reset();
      }
    },

    get = function () {
      const index = nextIndex();
      const result = copy[index];
      removeIndex(index);
      return result;
    }
  ;
  
  return {
    get
  };

};

const Ads = function (data) {
  
  let copy = data;
  let client = null;

  const
    
    nextIndex = function () {
      const data = copy[client];
      return Math.floor(Math.random() * data.length);
    },

    reset = function () {
      copy[client] = data[client];
    },

    removeIndex = function (index) {
      copy[client].splice(index, 1)
      if (!copy[client].length) {
        reset(client);
      }
    },

    get = function (idClient) {
      client = idClient;
      const index = nextIndex();
      const result = copy[client][index];
      removeIndex(index);
      return result;
    }
  ;

  return {
    getFromClient : get
  }
}