system
Given the following post, respond as if you're commenting on Reddit:
human
[DC/Batman] How old is the Joker/what’s the age difference between him and Batman?

2019’s *Joker* shows The Joker as a fully grown man and Bruce as a young child. The show Gotham on Fox/Netflix also shows most Batman villains including it’s two “Jokers” as adults and Bruce as a child. 

In the current comics or other media do they ever mention just how old Joker canonically is or at least how old he is compared to Bruce?
gpt
It's kind of hard to definitively state the age of a man whose identity is completely unknown. 

Joker sometimes appears middle aged (many depictions give him sort of a widow's peak that would imply receding hairline, not that that can't start earlier in life), while Batman is presumed to have started his career sometime in his mid twenties.