How can i use Unicode string key In Javascript Object?

I want to use unicode string in Object as key, something as:

var t = {"姓名": "naitong"};

it's ok , t["姓名"] return "naitong"

but

Object.keys({"姓名": "naitong"})

I got " ", a blank string

Anyone knowes why?

Editting:

I install firebug and try it in the console, it works. Acctually i use mozrepl, so that i can editing and run javascript in emacs. So This have something to do with mozrepl

I have confirm that mozrepl support only "7bit safe ASCII", to tranform unicode ,i have to json-encode it in emacs, as:

alert(Object.keys(JSON.parse("{\"\\u59d3\\u540d\":\"naitong\"}")))

This is my first question asked on stackoverflow, and i got quick resp. Thank you all.