How to get copy response in NodeJS?

I'm running the copy from stdin command from node.js just like this site suggests to do: https://gist.github.com/soldair/5168249
But, I don't know how to get the result of the copy command. For instance, I've copied in data and the data doesn't fit the table, so no rows get inserted. When I do this from dbvisualizer, it doesn't give me an error, but it says that 0 rows were affected. I don't know how to get those results from node.js.
Thanks,
Kim