if (!loadedSkins.hasOwnProperty(skin)) {
                    // Download skin
                    loadedSkins[skin] = new Image;
                    for(var i = 0; i < SKIN_URL.length; i++){
                        for(var j = 0; j < SKIN_EXT.length; j++){
                            $.ajax({
                                url:'http://agara.co/' + SKIN_URL[i] + skin + SKIN_EXT[j],
                                type:'HEAD',
                                error: function(){
                                    //file not exists
                                    continue;
                                },
                                success: function(){
                                //file exists
                                    loadedSkins[skin].src = SKIN_URL[i] + skin + SKIN_EXT[j];
                                    break;
                                }
                            });
                        }
                    }
                }