Cannot update a component while rendering a different Component - ReactJS - reactjs

Question

I know lots of developers had similar kinds of issues in the past like this. I went through most of them, but couldn't crack the issue.
I am trying to update the cart Context counter value. Following is the code(store/userCartContext.js file)
import React, { createContext, useState } from "react";
const UserCartContext = createContext({
userCartCTX: [],
userCartAddCTX: () => {},
userCartLength: 0
});
export function UserCartContextProvider(props) {
const [userCartStore, setUserCartStore] = useState([]);
const addCartProduct = (value) => {
setUserCartStore((prevState) => {
return [...prevState, value];
});
};
const userCartCounterUpdate = (id, value) => {
console.log("hello dolly");
// setTimeout(() => {
setUserCartStore((prevState) => {
return prevState.map((item) => {
if (item.id === id) {
return { ...item, productCount: value };
}
return item;
});
});
// }, 50);
};
const context = {
userCartCTX: userCartStore,
userCartAddCTX: addCartProduct,
userCartLength: userCartStore.length,
userCartCounterUpdateCTX: userCartCounterUpdate
};
return (
<UserCartContext.Provider value={context}>
{props.children}
</UserCartContext.Provider>
);
}
export default UserCartContext;
Here I have commented out the setTimeout function. If I use setTimeout, it works perfectly. But I am not sure whether it's the correct way.
In cartItemEach.js file I use the following code to update the context
const counterChangeHandler = (value) => {
let counterVal = value;
userCartBlockCTX.userCartCounterUpdateCTX(props.details.id, counterVal);
};
CodeSandBox Link: https://codesandbox.io/s/react-learnable-one-1z5td
Issue happens when I update the counter inside the CART popup. If you update the counter only once, there won't be any error. But when you change the counter more than once this error pops up inside the console. Even though this error arises, it's not affecting the overall code. The updated counter value gets stored inside the state in Context.

Answer 1

TIL that you cannot call a setState function from within a function passed into another setState function. Within a function passed into a setState function, you should just focus on changing that state. You can use useEffect to cause that state change to trigger another state change.
Here is one way to rewrite the Counter class to avoid the warning you're getting:
const decrementHandler = () => {
setNumber((prevState) => {
if (prevState === 0) {
return 0;
}
return prevState - 1;
});
};
const incrementHandler = () => {
setNumber((prevState) => {
return prevState + 1;
});
};
useEffect(() => {
props.onCounterChange(props.currentCounterVal);
}, [props.currentCounterVal]);
// or [props.onCounterChange, props.currentCounterVal] if onCounterChange can change
It's unclear to me whether the useEffect needs to be inside the Counter class though; you could potentially move the useEffect outside to the parent, given that both the current value and callback are provided by the parent. But that's up to you and exactly what you're trying to accomplish.