map.js

(function() {
  'use strict';

  if (window.Map) return;
  window.Map = FakeMap;

  function FakeMap() {
    this._keys = [];
    this._values = [];
  }

  FakeMap.prototype = {

    has: function(key) {
      return this._keys.indexOf(key) !== -1;
    },

    get: function(key) {
      var index = this._keys.indexOf(key);
      if (index === -1) return;
      return this._values[index];
    },

    set: function(key, value) {
      var index = this._keys.indexOf(key);
      if (index === -1)
        index = this._keys.length;

      this._keys[index] = key;
      this._values[index] = value;
    },

    delete: function(key) {
      var index = this._keys.indexOf(key);
      if (index === -1) return;

      this._keys.splice(index, 1);
      this._values.splice(index, 1);
    },

  };

})();