reduxjs/reselect v5.0.0-beta.0

on GitHub

This beta release updates createSelector to accept additional memoization functions and memoizer options directly (without needing to use createSelectorCreator first), renames an experimental memoizer to unstable_autotrackMemoizer for clarity, and drops support for TS 4.6 and earlier.

npm i reselect@beta

yarn add reselect@beta

This is part of the in-progress Redux Toolkit 2.0 beta work, and Reselect 5.0 will be included with Redux Toolkit 2.0 when it is released. Please try out RTK 2.0 beta and give us feedback!

Changelog

New / Improved createSelector Memoization Options

Originally, the only way to customize createSelector's behavior (such as using an alternate memoization function) was to first create a customized version via createSelectorCreator(memoizerFunction, memoizerOptions). This was typically used for creating use cases like deep equality comparisons with _.equal instead of shallow equality, as well as alternate memoizers that had a notion of cache size.

With Reselect 4.1.0, we added the ability to pass memoizer options directly to createSelector, and also updated defaultMemoize to accept several options such as a max cache size. This meant that you could call createSelector(...inputFns, outputFn, {memoizeOptions: {maxSize: 100}}), but you couldn't change the memoizer _function_ being used directly - that still required use of createSelectorCreator`.

Additionally, Reselect internally uses the provided memoizer function twice internally: once on the overall arguments passed to selectSomeValue(a, b, c), and a second time on the values extracted by the input functions such as state => state.a. There have been multiple issues over the years where users wanted to provide separate memoization functions for the arguments vs the extracted values, such as a reference equality check for the arguments and a shallow check for the extracted values.

With this release, you can now pass alternate memoizer functions directly to createSelector, and both createSelector and createSelectorCreator accept separate options for memoize and argsMemoize (along with any options for those):

const selectTodoIds = createSelector(
  (state: TodoState) => state.todos,
  todos => todos.map(({ id }) => id),
  {
    memoize: defaultMemoize,
    memoizeOptions: {
      resultEqualityCheck: (a, b) => a === b
    }
    argsMemoize: microMemoize,
    argsMemoizeOptions: { 
      isEqual: (a, b) => a === b 
    },
  }
)

This should mostly eliminate the need to use createSelectorCreator for customization. (You can still use it for encapsulation / reuse if you want to create many selectors with the same customization options.)

Thanks to @aryaemami59 for some incredibly comprehensive efforts reworking the internals of createSelector, our TS types, and the codebase structure in order to make this possible!

Other Changes

We've dropped support for TS 4.6 and earlier. Our current TS support matrix is TS 4.7+.

The experimental autotrackMemoize function has been renamed to unstable_autotrackeMemoize. It will still be exported, but it needs significant further testing before we consider it ready.

What's Changed

• Drop support for TS 4.6 and earlier, and update CI to use latest RTK betas by @markerikson in #630
• Allow passing in memoize functions directly to createSelector. by @aryaemami59 in #626
• Rename to unstable_autotrackMemoize and bump Vitest version by @markerikson in #631

Full Changelog: v5.0.0-alpha.2...v5.0.0-beta.0