More likely they don't even need to use useMemo if it's not an expensive calculation. They can just calculate the dependent values during rendering, which is explained in the docs: https://react.dev/learn/you-might-not-need-an-effect#updatin...
If `getLinkedCats` calls an external API, then the calculation can instead be all in the same useEffect.
The number one mistake I see people inexperienced with React doing is using too many useEffect's in their code, which is both hard to read and hurts performance, since it results in more renders than necessary.
I'll point out that just on this comment string from telmac are 3 different interpretations of what is wrong with the code and what should be done instead.
Yes, it's bad code, and aren't we all having fun laughing at the anonymous dev who wrote it.
However, I've seen this kind of code in the wild, and I'd be shocked if you hadn't, too. _Who_ wrote it matters a lot less than the fact that _so many people_ write it. I think that React has optimized for developer velocity, but the primitives make it so easy to shoot yourself in the foot, that in a large codebase with lots of devs, it becomes hard to avoid.
> the bit where he complains about the two useEffects, that's indeed disgusting but that's because whoever wrote it is an idiot, that should be useMemo, and then it would be obvious to read etc.
Given that of the three dependency items between the two useEffects, only one is actually used in the useEffect where it is listed as a dependency, there are deeper problems than using useEffect where they should probably be using useMemo there, but, yeah, it definitely looks like code written by someone clueless about React basics.
>So, this entire rant about React... it's not even React's fault. Neither is Angular's, or jQuery's. Simply, whichever tech you choose will inevitably crumble down under the impossible complexity of building a reactive UI.
and then he's like "ok the solution is to just not make big interactive software" and I'm like bro that is the opposite of a solution
separately, and I'm not sure how much this is really a nitpick: the bit where he complains about the two useEffects, that's indeed disgusting but that's because whoever wrote it is an idiot, that should be useMemo, and then it would be obvious to read etc. (well, maybe besides dependency arrays being at the end) -- more broadly I'm a bit like "I think you spent <10 hours using a framework, found it confusing, and got buttmad", which, whom among us, but also once again "bro if you just actually read the docs and spend time with it it's fine"