[javascript] Encoding Javascript Object to Json string

I want to encode a Javascript object into a JSON string and I am having considerable difficulties.

The Object looks something like this

new_tweets[k]['tweet_id'] = 98745521;
new_tweets[k]['user_id'] = 54875;       
new_tweets[k]['data']['in_reply_to_screen_name'] = "other_user";
new_tweets[k]['data']['text'] = "tweet text";

I want to get this into a JSON string to put it into an ajax request.

{'k':{'tweet_id':98745521,'user_id':54875, 'data':{...}}}

you get the picture. No matter what I do, it just doesn't work. All the JSON encoders like json2 and such produce

[]

Well, that does not help me. Basically I would like to have something like the php encodejson function.

You can use JSON.stringify like:

JSON.stringify(new_tweets);