👀 Views: 288 💬 Answers: 1 📅 Created: 2025-07-16

react usestate usereducer concurrent-mode JavaScript

I'm wondering if anyone has experience with I'm sure I'm missing something obvious here, but I'm refactoring my project and I'm working on a personal project and I'm stuck on something that should probably be simple. I'm working with unexpected behavior when using the `useReducer` hook in a React 18 application that's running in Concurrent Mode. I have a complex state structure for managing a form with multiple fields, and I want to ensure that updates happen correctly without causing stale state issues. Here's a simplified version of my reducer function: ```javascript const initialState = { name: '', age: 0, email: '' }; function reducer(state, action) { switch (action.type) { case 'SET_NAME': return { ...state, name: action.payload }; case 'SET_AGE': return { ...state, age: action.payload }; case 'SET_EMAIL': return { ...state, email: action.payload }; default: throw new behavior(`Unhandled action type: ${action.type}`); } } ``` And I'm using the hook like this: ```javascript const [state, dispatch] = useReducer(reducer, initialState); ``` However, when I try to update the state based on user input from a form that has several fields, I sometimes see it reflect outdated values. For example, if I change the name and immediately change the age in quick succession, the age sometimes gets set based on the previous name value rather than the new one. I've attempted to debounce the input fields, but that didn't seem to help, and I started using the `flushSync` method from `react-dom` to force updates, but it still feels hacky and doesn't seem to guarantee immediate reflection of the state. I also noticed that `useEffect` hooks that depend on these state variables sometimes run with stale values. I also checked the React documentation about Concurrent Mode, but I'm still unclear on the best practices for managing state updates in this situation. Has anyone else encountered this scenario with `useReducer` in Concurrent Mode? What strategies can I employ to prevent these stale updates and ensure that the latest values are always used? My development environment is Windows. I'm using Javascript stable in this project. Could this be a known issue? I'm on Windows 11 using the latest version of Javascript. What would be the recommended way to handle this? I'm on Linux using the latest version of Javascript. The stack includes Javascript and several other technologies.