A simple .new() method to create instances without constructors. This allow us to rewrite the "new" in order to do other things but create objects.

new.js

function $new() {
  var obj = Object.create(this);
  obj.init.apply(obj, arguments);
  return obj;
}

usage.js

var SimpleMap = {
  
  new: $new,
  
  init: function() {
    this._map = Object.create(null);
  },
  
  get: function(key) {
    return this._map[key];
  },
  
  set: function(key, value) {
    return this._map[key] = value;
  }
};

var map = SimpleMap.new();

porque usar Object.create(null) en vez de {} ?

Object.create() set's the prototype of the new object to the value you pass to it
{} creates a object which prototype is Object.prototype