Not sure why hasOwnProperty() seems to be missing from my object...

I'm getting data from an http post in expressjs3, like this:

someControllerFunction: function(req, res){

            var data = req.body.loc;

...

}

However if I do:

data.hasOwnProperty('test'); 

I get:

Object object has no method 'hasOwnProperty' 

Perhaps I'm missing something obvious, but what?

(Node 10.5, Express 3.2.1)