This release updates createReducer/createSlice to ensure initial state gets frozen, optimizes the performance of the immutability and serializability dev check middleware, and re-exports the original and isDraft APIs from Immer.
Changes
Freezing Initial State
Immer has always frozen its result states in development, and as of Immer 8, does so in production as well. Since both createReducer and createSlice use Immer, all their result states get frozen.
However, the initial state was never being run through Immer, and thus was never being frozen. That meant it was actually possible to mutate initial state values.
We now run the initial state through an Immer no-op reducer, just to ensure that it's properly frozen at all times.
Dev Check Middleware Optimizations
The immutability and serializability dev check middleware act as safety rails to catch common mistakes. However, both of them do so by running deep recursive checks on all of your Redux state, after every dispatched action. Those deep checks are often very expensive, especially as your state grows larger, and the performance can add noticeable lag in dev. RTK offers options for turning them off or ignoring specific slices of state, and warns if they're taking too long, but those are escape hatches we would rather people not use because they lose the safety benefits.
In this release, we've optimized both middleware to run significantly faster.
The immutability middleware now considers frozen objects to be immutable by default, and will stop recursing when it sees a frozen value. This means that in most cases, the runtime of the immutability middleware is effectively 0ms, as it only has to do a few quick checks on your root state slice values without going any deeper. We've also optimized the nested keypath calculation logic, which cuts down on runtime significantly if it does actually have to recurse.
We've also applied the keypath optimizations to the serializability middleware as well. While this middleware can't benefit from the frozen checks, the keypath optimizations have cut its runtime down by about 70% in benchmarks.
Additional Immer Re-Exports
We now export the original and isDraft APIs from Immer for completeness.
This release also updates the Immer dependency to 8.0.1+ to address a vulnerability in Immer. Our dependency was already 8.0.0+, so strictly speaking no update was necessary - users just needed to update their own local dependencies to get the newer Immer version.
Docs Updates
We've made several updates to the RTK docs:
- The existing tutorials in the RTK docs site have been removed, and we now point to the "Redux Essentials" and the "Redux Fundamentals" tutorials in the Redux core docs so that there's only one place to have to read through tutorials
- We've added a couple "quick start" tutorial pages that show the bare basics of setting up RTK and using it with TypeScript
Changelog
- Export isDraft from Immer (#944 - @markerikson)
- Optimize dev check middleware performance (#943 - @markerikson)
- Freeze initial state by passing through Immer (#940 - @markerikson)
- fix: vulnerability in immer (#909 - @i1skn
- re-export original from immer (#832- @jackielii)