Reselects

Reselects is the plural form of the verb reselect, meaning to select again after an initial choice. In common usage, it describes processes in which a decision-or item is reconsidered, such as reselecting a candidate for a role, reselecting a shipping option, or reevaluating choices in a form or workflow. The term can refer to both human decision processes and technical procedures that involve deriving a new selection from existing options. In many contexts, reselecting implies a refinement or adjustment of an earlier outcome.

In computing, reselects often refers to the JavaScript library Reselect, used with Redux to create memoized selectors for derived state. The library provides a function called createSelector to compose input selectors with a final result function. The key idea is to cache the computed output and return the cached value if the input state has not changed, avoiding unnecessary recalculation. Selectors can be composed, enabling modular, reusable logic to derive data such as filtered lists, sums, or counts from a store.

Usage considerations include the need for immutable state to ensure equality checks work as intended; mutable updates can invalidate the cache and lead to incorrect recomputations. Performance gains depend on the complexity of the derived data and the frequency of changes. Reselect is commonly paired with React-Redux, where selectors feed mapStateToProps and reduce re-renders.