You should use withMutations when you want to group several changes on an object. Because each change creates a clone, several changes in a row cause several clones. Use withMutations to apply several changes then clone once at the end. A clone at every step means that you are reading the entire list for each … Read more
TL;DR; No, but using Records you can get Flow to typecheck the shape but not the types. Longform The correct answer would be: no, since maps don’t have shapes (at least in Flow and Immutable). But Immutable does have a type for “Maps” with shapes. That would be Records. But for reasons described below (since … Read more
There is an open ticket to improve the API which is on the roadmap for 4.0. Until this is implemented, I suggest you use Immutable.Iterable.isIterable() (docs). Using instanceof is not reliable (e. g. returns false when different modules use different copies of Immutable.js)
Personally I prefer the merge syntax, it feels more natural: const newContent = oldContext.merge({ “logged”: true, “error”: false }); If you were doing something very complex, maybe the transient version would be better, but I just can’t imagine where. It also means you can leverage mergeDeep if needed.