react-use-state

Pass an updater function to the setter, such as setCount(c => c + 1), instead of referencing the state variable directly. This queues updates against the latest value, so multiple sequential calls accumulate correctly rather than reusing a stale snapshot.

Use useState for simple, local state with direct value replacement. Switch to useReducer when state has multiple related sub-values, next state depends on previous state in complex ways, or you want to centralize transition logic in a reducer function.

State updates are asynchronous and batched, so the state variable keeps its old value within the same render. Compute the next value into a local variable if you need it immediately, or use an updater function for subsequent updates.

React relies on reference comparison to detect changes, so mutating an object or array in place and passing the same reference to the setter is ignored. Always create a new object or array using spread syntax, map, or filter.

No, values computable from props or other state should be calculated during render instead of stored. For expensive computations, wrap the calculation in useMemo to avoid redundant work on every render.