According to JK :
Any issues with wiring lamp wire to 14/2 wire? I am going to wire some
undercabinet lights to a switch. I was going to use a transformer, but the
HD guy said no need to. Just run the lamp wire from the lights into a
junction box, and connect it to the wire (14/2, since it will be going
through my attic) coming from the switch. Is that okay?

Lampcord MUST NEVER enter a J-box.

Put a receptacle on the junction box (or wire another receptacle nearby),
and plug the lamp cord into it.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.