NodeJS url.parse( url ).query

In the nodejs documentation:

query: Either the 'params' portion of the query string, or a querystring-parsed object. Example: 'query=string' or {'query':'string'}

Link: NodeJS URL

This part is confusing.

1. When will 'query=string' happens?
2. When will this {'query':'string'} also happens?

I have seen that when I do url.parse() it automatically converts the parameters into an object. My code will be buggy if I only support one format.

How will I know if url.parse() converts the parameters in this format: 'query=string'?