JS：如何获得关联数组的第一个N元素

I have that J Stsrutcure:

我有J Stsrutcure:

var rooms={};
rooms["room1"] = 10;
rooms["room2"] = 25;
rooms["room3"] = 15;
rooms["room4"] = 1;
rooms["room5"] = 10;
rooms["room6"] = 181;
rooms["somrthing"] = value;
v