var hashMap = { 
  Set : function(key,value){this[key] = value}, 
  Get : function(key){return this[key]}, 
  Contains : function(key){return this.Get(key) == null?false:true}, 
  Remove : function(key){delete this[key]} 
} 

hashMap.Set("name","John Smith"); 
hashMap.Set("age",24); 
hashMap.Get("name");//John Smith 
hashMap.Contains("title");//false 
hashMap.Contains("name");//true 
hashMap.Remove("age"); 

var map = {};
'toString' in map; // true

var map = {};
map.hasOwnProperty('toString'); // false

var map = {};
map.hasOwnProperty = 'foo';
map.hasOwnProperty('hasOwnproperty'); // TypeError

var map = {};
map.hasOwnProperty = 'foo';
{}.hasOwnProperty.call(map, 'hasOwnproperty'); // true

var map = {};
var has = {}.hasOwnProperty;

for(var key in map){
 if(has.call(map, key)){
  // do something
 }
}

var obj = {};
// is equivalent to:
var obj = Object.create(Object.prototype);

var map = Object.create(null);

map instanceof Object; // false
Object.prototype.isPrototypeOf(map); // false
Object.getPrototypeOf(map); // null

var map = Object.create(null);
map + ""; // TypeError: Cannot convert object to primitive value

var map = Object.create(null);
'toString' in map; // false

var map = Object.create(null);

for(var key in map){
 // do something
}

var map = Object.create(null);

Object.defineProperties(map, {
 'foo': {
  value: 1,
  enumerable: true
 },
 'bar': {
  value: 2,
  enumerable: false
 }
});

map.foo; // 1
map['bar']; // 2

JSON.stringify(map); // {"foo":1}

{}.hasOwnProperty.call(map, 'foo'); // true
{}.propertyIsEnumerable.call(map, 'bar'); // false

var map = Object.create(null);

typeof map; // object
{}.toString.call(map); // [object Object]
{}.valueOf.call(map); // Object {}