Code that only runs once when a React component's state updates

Question

I have a react component called index.tsx in my game project which has a variable that updates the state, assuming that the component refreshes every time the user's balance changes.

I'm creating a "net position" function where when starting the game the user's balance is saved as a reference value and then only additions and subtractions for each transaction should be made from that reference value.

Assuming the user has a balance of $5000 at the beginning (in the footerBalance variable), the Net Position label will show that value as 0 (in the netPositionBalance variable), with $5000 as the base. Now the user wins $100 in the next game, his balance will become $5100 (in the footerBalance variable) and the net position will become $100 (in the netPositionBalance variable).

What happens now is that once the balance is updated, my net position amount is also updated, and since it's in the same component file, the net position becomes 0.

I hope this is fixed at the beginning and that this particular code should not re-render, no matter how the component refreshes.

The code block to obtain the balance is as follows:

const footerBalance = useAppSelector(state => state.app.footerUnformattedBalance); //This will change the balance, i.e. it will give $5000 after winning $100 Afterwards, it will become $5100

I need a variable called footerBalanceAtStart so that I can display the net position (in the variable netPositionBalance) from the starting point, similar to the following:

let netPositionBalance = Number(footerBalanceAtStart) - Number(footerBalance); //During the game, it should be updated to $100

I would like "footerBalanceAtStart" to be defined to only get the balance once and then remain constant for the entire duration of the project.

Answer 1

So I found the answer. Apparently I can also use useEffect here, like this:

const [footerBalanceAtStart, setAny] = useState(footerBalance);

Now it will only store the value once and will not change automatically without the state update function setAny()