jquery创建类似java map的键值对集合

今天发现在IE9模式下js的Map不起作用，
var map=new Map();//报错：Unresolved type Map

修改如下：
var map = {}; // Map map = new HashMap();
map[key] = value; // map.put(key, value);
var value = map[key]; // Object value = map.get(key);
var has = key in map; // boolean has = map.containsKey(key);
delete map[key]; // map.remove(key);