Just refactored this only for the sake of my eyes..

Nice job, but why the seemingly useless variable assignment?

@anroven you're right, changed it!

@aktane the final result is practically one line

Shouldn't you keep that first if statement?

@shellbug I could, but the reducer has a default initial state to be an empty array, so it is not necessary

@DiegoCaceres oh, cool. I didn't notice the redux tag. I guess that's a selector then?

@shellbug yes! That's it :)

Nice refactor! 😎
But it depends on the length of the array.
After all last i've checked the for-loop has the best performance than all the other loops.

Also assuming the browser will automatically choose the for-loop, there is still the case in which the object 'list.allIds' is not an array and subsequently the code will fail.