Exactly! Too many incorrect tutorials for beginners on the internet. Where there's no control over the content huge amount of beginners start on the wrong foot which btw haunts them for many many years ahead...

indeed, I actually found it quite triggering that he said "this is the correct way to do it" multiple times, while showing what react docs brings up as an anti pattern. I mean I know this is just an example, but still, make the example correct also

Use like the example before, with usememo, pass the nextcard and round as parameters

we can call that function in the useEffect with empty dependency or based on the event(like button click)

@@bharathnaidu4636 You could, but then you need to watch the video again, cuz you missed the point.

@@bharathnaidu4636 I hope that's a troll haha

@@o_glethorpe ah yeah that would make sense, thx

The more they should in performance / clean code. If nobody minds / cares about it because of the "time crunch", then your company will touchwood fail due to the inefficient and ineffective coding which leads to spagette codes. Yes you can don't mind the patchwork your company does, the latter part will be it is the future ones that has to keep patching until some drops a nuke bomb to nuke it cleanly and does it well.

The react documentation is very clear about this: Use useEffect if you are dealing with an external source.

@@o_glethorpe Very true, useEffect is not for this type of thing, use useEffect for subscribing/communicating something from an external source (API Calls, store libraries that are outside of react ecosystem)

It won't change if anything other than items or filters changes. In this example you can assume filters has been memorized in the parent

Use memo doesn't do async stuff! You still need useEffect to fetch data

He would probably call it in a button to draw a new card, removing the need of a useEffect

The reason is for increasing performance, which is not always needed, and I've read that using useMemo itself creates a set amount of processor cost, which may often be greater than the un-memoized function. In your example, the filteredItems variable will be computed on every single render, even if items and filters had the exact same value on the previous render, making the re-computation unnecessary. When useMemo is applied, the computed value will not be re-computed during the render - instead the previous value will be used. If there are thousands of items in that items variable, you will definitely notice an improvement in the UI responsiveness. There are examples in the new React docs that demonstrate the difference that it makes. But if you knew that items was always a fixed value, like a set of 15 colors or something, then maybe it would be faster not to use useMemo, because of the overhead cost that it requires. Or is said to require, I should say.

@@TokyoXtreme I am saying just declaring as a variable, non useMemo

@@TokyoXtreme yeah of you need to deep compare

@@frazuppi4897 filteredItems is a computed value, which doesn't have to be memoized; but if the calculation is costly and time-consuming, then memoizing will increase performance noticably.

@@TokyoXtreme no beucase it will rerun only if the props changes, thus is If just have a computed value will be the same since in that case the components will rerender I guess

It will be the same while in this function. Read about it more searching for: "state batching in react"

in the "if(round == 5)" the round variable is not the updated version

In the jsx

It's a simple example, why bother? He could of course just made the first if statement a guard instead; if (!nextCard.isGold) { return; }

Not really, you can always change that anyway to make it "prettier", but the logic is good.

yup, "if (!nextCard.isGold) return" would help get rid of 1 level

@@programmers_sanctuary here watch this video in aspects of chaining if else v=EumXak7TyQ0. Not a spam, just that on a neutral perspective the true objectives for a developer besides developing features / solving bugs are: 1. Readable code. 2. Can the code be simplified to understand easily? 3. Should this code be a function as it is being repeated? 4. etc.... If your mindset is just content to solve codes, the others hope that it isn't long and spaghetti.

When any value changes there needs to be a re-render yes, but only one. So only when items changes. That's with useMemo. With useEffect there's 2, when items changes and then selectedItems after that

You don’t need it, but the useMemo will save the result so the function isn’t called on every render unless the dependencies change. Probably only needed if the function is doing a lot of heavy processing.

@@chrisjohanesen Got it. I just wonder if render will be affected differently with useMemo. I mean, if we have only filters and items as props/state then UI will be rendered anyway.

check if your card supports USD

that processing is unnecessary and doesn't have to be there, so why would we add it ourselves?

@@cosdensolutions I agree in this case it's just a simple filter, but maybe the filtering is done on the server side, this way we have to wait for the data to load I think, so it depends

in this case maybe it wouldn't make sense because filterItems is not async but anyways I'm discussing the idea

Ah yes why sky is blue, google is your answer

The hook is designed to synchronize components with external systems - outside of React. If you have to fiddle with browser APIs or other side effects, then that's why you'd use useEffect. In the example here, of the card game, there is only the loop of user interacting via JSX UI elements (buttons, probably), which update state and trigger a re-render. The new UI can be completely derived from the current state, so it's glaringly obvious that useEffect is not needed. Perhaps if cards were being saved in browser's localStorage, then useEffect would be needed.

They noticed that React 19 does not include the Compiler. The Compiler (React.forget) will come long after React 19. So, we've been convinced for a long time that memoization is a neat way to improve React performance.

@@user-qj4rr1rm8i what you on about? react 19 will come with its own compilers thus will no need useMemo stuff

Tbh, clients are idiots that they bargain towards marketing / client service group. But the root problem lies internally, whereby the boss / higher ups doesn't care after patchwork of projects how do we as a programmer do small steps to not create more problems. That is the real issue.

But Clients care about speed, using useEffect for this thing would add 1 more render to the component, this render will give another overhead and affects your overall app speed

It's the same

Wat

useEffect is meant for synchronizing with external systems outside of React - so which external system is being synchronized here? There's nothing that can't be derived from user interaction, props, and state, so there's no need for useEffect. Can you answer which "side effect" needs to be synchronized?

No, the react official doc also says that don't use useEffect for this type of thing, you are in the wrong here

@@TokyoXtreme in the new doc they advice it, in the old doc they didnt... Its a fact React query is the most powerfull process to fecth datas, forget useffect for this use case

@@lord_kh4n i am just speaking about "cost",some time you dont have other choices to use useeffect or useMemo, But the memory cost is sup than rendering. Its why you use it, only for function/variables using a lot of power.

correction, everywhere may contain bugs

@@yawn74 most of that bug in useEffect

congrats!