Send URL-encoded parameters in Node.js using request module

I am trying to create a new paste using the PasteBin API with request module like so:

var request = require("request");
request({
    url : "http://pastebin.com/api/api_post.php",
    method : "POST",
    qs : {
        "api_dev_key" : MY_DEV_KEY,
        "api_option" : "paste",
        "api_paste_code" : "random text"
    }
},function(err,res,body){
    ...
});  

My understanding is that since the method is POST and querystring parameters are provided, the values in qs object will be stored as key=value pairs in the body. (Ref: How are parameters sent in an HTTP POST request?)

However, I get back a Bad API request, invalid api_option from PasteBin. So I curled the request from my terminal like so:

curl -X POST "http://pastebin.com/api/api_post.php" -d "api_dev_key=[MY_DEV_KEY]&api_option=paste&api_paste_code=some+random+text"  

and this worked.

So this leads to two questions:

1. How exactly are the parameters sent when a POST request is made and qs is provided?
2. How do I send URL-encoded body using just the request module?

Rename the qs key to form in the object. The qs key is for specifying the query string on the end of the URL (e.g. For GET requests). The form key is for specifying the form URL encoded request body (e.g. For a POST request).