React 18: Strange behavior when using multiple useMemo hooks for derived state calculations
Quick question that's been bugging me - I'm experimenting with I'm deploying to production and This might be a silly question, but I'm working on a project and hit a roadblock. I'm working with a puzzling scenario in my React 18 application where I'm using multiple `useMemo` hooks to calculate derived state based on props. The question arises when I notice that one of my memoized calculations does not seem to update correctly when the props change. Here's a simplified version of my code: ```javascript import React, { useMemo } from 'react'; const MyComponent = ({ data }) => { const transformedData = useMemo(() => { return data.map(item => item * 2); }, [data]); const total = useMemo(() => { return transformedData.reduce((acc, item) => acc + item, 0); }, [transformedData]); return <div>Total: {total}</div>; }; ``` In this scenario, the `transformedData` should update when `data` changes, which in turn should lead to `total` being recalculated. However, I noticed that when `data` is updated, `total` doesn't always reflect the expected result. The only time it seems to work correctly is when `data` contains the same reference (like when I use a static array) or when I force a re-render by toggling a state variable in the parent component. I've tried adding console logs within the `useMemo` hooks to verify whether they are actually being called on prop changes, but the logs show that `total` is only recalculated when `transformedData` runs—which seems unexpected. I also confirmed that my `data` prop is being correctly updated in the parent component and that different references are being passed. Is there something subtle I might be missing with the way I'm using `useMemo`? Could the scenario stem from how React handles memoization in this particular scenario? Any insights would be greatly appreciated! This is part of a larger service I'm building. Any ideas what could be causing this? This issue appeared after updating to Javascript 3.11. This is for a application running on macOS. Any suggestions would be helpful. I recently upgraded to Javascript 3.9. Any ideas what could be causing this?