(NextJS) What does this mean: "Because the Redux store is shared across requests"

[emreakdas]

"No global stores - Because the Redux store is shared across requests, it should not be defined as a global variable. Instead, the store should be created per request."

I came across this while reading the document, can you give an example for this scenario to occur? I did not fully understand what is meant by saying that the global store data may be contaminated.

and what problems can sharing your wishes cause?

[phryneas]

User A visits your page. Your page is executed in SSR, a global store variable is created.
User B visits your page. Your page is executed in SSR. The same global store variable is used.

Relevant knowledge: In Next.js, every client components will automatically SSR for the first render of a user session.

[emreakdas]

@phryneas

Aren't all the precautions you mentioned actually so that data is not accidentally written / read to the store on the server side? When data is not read and written on the server side, doesn't the store on the server only serve as an initial value used for ssr only in client usage?

If I'm only using redux on the client side. What kind of problem could that cause? Isn't the precaution just to protect the developer

[phryneas]

If I'm only using redux on the client side. What kind of problem could that cause? Isn't the precaution just to protect the developer

No, you're not, even if you only use it in "Client Components", you also use it Server Side. Client Components are rendered on the server.

Unless you have something like if (typeof window == "undefined") return null in your root component, your application will render on the server. (And if you did this, you'd get a hydration error every page load).
It's unavoidable, a core part of Next.js.

You shouldn't use any globals in a SSR-oriented framework like Next.js. It's just proper code hygiene.

[emreakdas]

when I say I'm using it, I mean this;

I just meant I write to the store in the client and read it.

--

After all, the data on the client will not go to the server, the store on the server will not change. (In the scenario where we do not write or read a value to the store on the server).

that's what I meant.

[emreakdas]

What I mean is that if data is written to the store on the server, we do it to prevent confusion. but in my case, it will not be written to the store on the server and will not be read, I hope I can explain.

[markerikson]

I'm sorry, but this conversation is going in circles and isn't helpful at this point. I'm going to lock the thread.