@U8ES68TGX Thanks for the response. The first point is good to know - I bet I have done that in my code. I found some other docs on it also, but I don't see it in the main docs yet: https://presumably.de/reagent-mysteries-part-1-vectors-and-sequences.html#gotchas ... About the keys and lists. I think I understand the need for keys and how they help performance with lists. I guess I am curious if keys are specific to list data structures or if they are also helpful for plain-old children. For example: [:div [:div] [:div]] vs [:div (list [:div] [:div])]. When using Clojurescript and into we can dynamically generate the first div from a list. I see some libraries do this (accept a list and into the list into a div). Do you know if React will make use of keys anyways in the first example?

@leblowl it is mentioned briefly here (item 4), but admittedly this is kind of out of the way https://github.com/reagent-project/reagent/blob/master/doc/FAQ/ComponentNotRerendering.md

in terms of your other question:

yes, there is a difference between [:div [:div] [:div]] vs [:div (list [:div] [:div])]. The latter version passes the sequence to react differently than the first version. React only attempts to do its key-based optimization if you pass using the later convention

there are lots of times when just using into is fine because you are not going to manipulate a sequence in a way that would allow the key optimization to do anything useful for you. e.g., if you are creating a drop-down menu from a map of keys, the elements in the dropdown are always going to be in the same order, so you really don’t need to invent keys

Good to know. Thanks for the reference to the docs too. I figured it was in there.