Access Mac localhost from Windows parallels
As mentioned in the comments above. 

localhost is the machine you are running on (Mac) so the VM (windows) will need to point to the IP address of your machine.

For example:

If you are viewing your application on your Mac at:
http://localhost:8080/#/users

Now if your Mac ip is 10.1.0.2, the url to view on the windows VM will be:
http://10.1.0.2:8080/#/users