A Sorta Kinda Map object. Use anything as a key, retrieves the associated value. Not as fast as a real map, but faster than an array.

Map

(function(){

    //***********************************************
    //
    //      A Sorta Kinda Map object
    //
    //***********************************************
    
    function fastEach(array, callback) {
        for (var i = 0; i < array.length; i++) {
            if(callback(array[i], i, array)) break;
        }
        return array;
    };
        
    function addToMap(key, value, store){
        if(key == null){
            throw "A non-null or undefined key is required";
            return;
        }
        
        var reference,
            type = typeof key,
            constructor;
        
        reference = store[type] = store[type] || {};
        
        if(type === 'object'){
            constructor = key.__proto__.constructor.name;
            reference = reference[constructor] = reference[constructor] || [];
        }else{
            reference = reference[key] = reference[key] || [];
        }   
        
        
        reference.push({key:key, value:value});
    };

    function getFromMap(key, store){
        var reference,
            type = typeof key,
            constructor,
            result;

        reference = store[type];
        
        if(!reference){
            return undefined;
        }
        
        if(type === 'object'){
            constructor = key.__proto__.constructor.name;
            reference = reference[constructor];
        }else{
            reference = reference[key];
        }
        
        if(!reference){
            return undefined;
        }
        
        fastEach(reference, function(item){
            if(item.key === key){
                result = item.value;
                return true;
            }
        });
        
        return result;
    };

    function MapCtor(){
        var store = {};
        
        function Map(){
        }
        Map.prototype.constructor = Map;
        Map.prototype.add = function(key, value){
            return addToMap(key, value, store);
        };
        Map.prototype.get = function(key){
            return getFromMap(key, store);
        };
        
        return new Map;
    }

    window.Map = function Map(){
        return MapCtor();
    }
})();

var map = new window.Map(),
    tests=[
            {
                key:{}, value: "plain object"
            },
            {
                key:{}, value: "diferent plain object"
            },
            {
                key:1, value: 1
            },
            {
                key:"1", value: "1"
            },
            {
                key: new Date(), value: "new Date()"
            }
      ];


tests.forEach(function(test){
    map.add(test.key, test.value);
});

tests.forEach(function(test){
    console.log(map.get(test.key) === test.value);
});