How to get first member of an object in javascript [duplicate]

Question

Possible Duplicate:
Access the first property of an object

I have a javascript object like this:

var list = {
    item1: "a",
    item2: "b",
    item3: "c",
    item4: "d"
};

Using reflection in JS, I can say list["item1"] to get or set each member programmatically, but I don't want to rely on the name of the member (object may be extended). So I want to get the first member of this object.

If I write the following code it returns undefined. Anybody knows how this can be done?

var first = list[0]; // this returns undefined

Answer 1

 for(var key in obj) break;
 // "key" is the first key here