chore: improve typing in devtools middleware by grigoriy-reshetniak · Pull Request #3362 · pmndrs/zustand

grigoriy-reshetniak · 2026-01-18T07:26:31Z

Summary

While going after another FIXME comment I've noticed repetitive api as any in devtools middleware. Also fixed some as any on the way.

Check List

pnpm run fix for formatting and linting code and docs
npx tsc --noEmit to check ts errors

vercel · 2026-01-18T07:26:51Z

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codesandbox-ci · 2026-01-18T07:26:53Z

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pkg-pr-new · 2026-01-18T07:27:10Z

demo
starter
```
npm i https://pkg.pr.new/zustand@3362
```

commit: ea4ba8d

dai-shi

If we were to do api as typeof api & WithDispatch, should WithDispatch have optional properties?

dai-shi · 2026-01-18T07:31:45Z

 }

+type WithDispatch = {
+  dispatch: (...args: any[]) => any


Can we avoid any here?

dai-shi · 2026-01-18T07:32:27Z

  (fn, devtoolsOptions = {}) =>
  (set, get, api) => {
    const { enabled, anonymousActionType, store, ...options } = devtoolsOptions
+    const apiWithDispatch = api as typeof api & WithDispatch


This increases bundle size. We hope only type improvements without affecting the result of bundling.

Removed this in favor of type guard. Now bundle size became smaller than before.

grigoriy-reshetniak · 2026-01-18T14:18:53Z

Hello @dai-shi.
Thank you for your review!

If we were to do api as typeof api & WithDispatch, should WithDispatch have optional properties?

You right, but I already removed this line for other reason.

dai-shi

Nice. The type guard approach is more reasonable.

dai-shi · 2026-01-18T21:37:34Z

+  dispatchFromDevtools: true
+}
+
+const hasDispatch = (api: unknown): api is WithDispatch =>


Actually, the name is confusing. This is not to check if it has the function, but if devtools should dispatch.

Suggested change

const hasDispatch = (api: unknown): api is WithDispatch =>

const shouldDispatchFromUs = (api: unknown): api is WithDispatch =>

Done, but the name is slightly different.

dai-shi · 2026-01-18T21:38:11Z

+  typeof (api as WithDispatch).dispatch === 'function' &&
+  (api as WithDispatch).dispatchFromDevtools


Let's keep the original order:

Suggested change

typeof (api as WithDispatch).dispatch === 'function' &&

(api as WithDispatch).dispatchFromDevtools

(api as WithDispatch).dispatchFromDevtools &&

typeof (api as WithDispatch).dispatch === 'function'

dai-shi · 2026-01-18T21:38:39Z


+type WithDispatch = {
+  dispatch: (...args: unknown[]) => void
+  dispatchFromDevtools: true


Suggested change

dispatchFromDevtools: true

dispatchFromDevtools: unknown

should be more precise.

dai-shi · 2026-01-19T12:40:00Z

+}
+
+const shouldDispatchFromDevtools = (api: unknown): api is WithDispatch =>
+  (api as WithDispatch).dispatchFromDevtools === true &&


Let's not change the logic.

Suggested change

(api as WithDispatch).dispatchFromDevtools === true &&

(api as WithDispatch).dispatchFromDevtools &&

Sorry, but this is required since dispatchFromDevtools is unknown now. The intent of shouldDispatchFromDevtools not only check if fields are existing, but that dispatchFromDevtools is true. If this is not done it won't fully substitute original behavior.

Also, leaving (api as WithDispatch).dispatchFromDevtools intact throws a TS error:

Type unknown is not assignable to type boolean

We didn't check if it's true, only if it's truthy. That's the original behavior. Do some workaround for the TS error. You can move it back to true from unknown if there's no workaround.

Updated. I picked !! over Boolean() because double negation already has been used in the repository.

Ah, I see. It was because of the type guard.

dai-shi

#3362 (comment)

dai-shi

LGTM
Thanks for your contribution!

grigoriy-reshetniak · 2026-01-20T04:57:45Z

Thank you for guiding me through this.

Bumps [zustand](https://github.com/pmndrs/zustand) from 5.0.10 to 5.0.11. Release notes *Sourced from [zustand's releases](https://github.com/pmndrs/zustand/releases).* > v5.0.11 > ------- > > This release includes small improvements in middleware thanks to contributors. > > What's Changed > -------------- > > * chore: improve typing in devtools middleware by [`@grigoriy-reshetniak`](https://github.com/grigoriy-reshetniak) in [pmndrs/zustand#3362](https://redirect.github.com/pmndrs/zustand/pull/3362) > * fix(persist): avoid relying on global localStorage by [`@honuuk`](https://github.com/honuuk) in [pmndrs/zustand#3367](https://redirect.github.com/pmndrs/zustand/pull/3367) > * fix(immer): Proper typing for immer middleware in combination with slices by [`@wheerd`](https://github.com/wheerd) in [pmndrs/zustand#3371](https://redirect.github.com/pmndrs/zustand/pull/3371) > > New Contributors > ---------------- > > * [`@SeongYongLee`](https://github.com/SeongYongLee) made their first contribution in [pmndrs/zustand#3355](https://redirect.github.com/pmndrs/zustand/pull/3355) > * [`@grigoriy-reshetniak`](https://github.com/grigoriy-reshetniak) made their first contribution in [pmndrs/zustand#3351](https://redirect.github.com/pmndrs/zustand/pull/3351) > * [`@DormancyWang`](https://github.com/DormancyWang) made their first contribution in [pmndrs/zustand#3363](https://redirect.github.com/pmndrs/zustand/pull/3363) > * [`@Ea-st-ring`](https://github.com/Ea-st-ring) made their first contribution in [pmndrs/zustand#3369](https://redirect.github.com/pmndrs/zustand/pull/3369) > * [`@winner07`](https://github.com/winner07) made their first contribution in [pmndrs/zustand#3373](https://redirect.github.com/pmndrs/zustand/pull/3373) > * [`@honuuk`](https://github.com/honuuk) made their first contribution in [pmndrs/zustand#3367](https://redirect.github.com/pmndrs/zustand/pull/3367) > * [`@wheerd`](https://github.com/wheerd) made their first contribution in [pmndrs/zustand#3371](https://redirect.github.com/pmndrs/zustand/pull/3371) > > **Full Changelog**: <pmndrs/zustand@v5.0.10...v5.0.11> Commits * [`99379a6`](pmndrs/zustand@99379a6) 5.0.11 * [`c81b4eb`](pmndrs/zustand@c81b4eb) chore(deps): update dev dependencies ([#3375](https://redirect.github.com/pmndrs/zustand/issues/3375)) * [`3871d53`](pmndrs/zustand@3871d53) fix(immer): Proper typing for immer middleware in combination with slices (#... * [`9b505ac`](pmndrs/zustand@9b505ac) fix(persist): use window.localStorage as default storage reference ([#3367](https://redirect.github.com/pmndrs/zustand/issues/3367)) * [`267a57c`](pmndrs/zustand@267a57c) Update code block in tutorial-tic-tac-toe.md ([#3373](https://redirect.github.com/pmndrs/zustand/issues/3373)) * [`6813f7b`](pmndrs/zustand@6813f7b) docs: remove stray Russian comment in beginner-typescript guide ([#3369](https://redirect.github.com/pmndrs/zustand/issues/3369)) * [`d9ea330`](pmndrs/zustand@d9ea330) docs(testing): fix undefined counterStoreRef variable ([#3368](https://redirect.github.com/pmndrs/zustand/issues/3368)) * [`6e026d7`](pmndrs/zustand@6e026d7) chore: improve typing in devtools middleware ([#3362](https://redirect.github.com/pmndrs/zustand/issues/3362)) * [`e7d4593`](pmndrs/zustand@e7d4593) Revert "chore(deps): bump pmndrs/docs/.github/workflows/build.yml from 2 to 3... * [`0f49ad8`](pmndrs/zustand@0f49ad8) chore(deps): bump pmndrs/docs/.github/workflows/build.yml from 2 to 3 ([#3364](https://redirect.github.com/pmndrs/zustand/issues/3364)) * Additional commits viewable in [compare view](pmndrs/zustand@v5.0.10...v5.0.11) [![Dependabot compatibility score](https://dependabot-badges.githubapp.com/badges/compatibility\_score?dependency-name=zustand&package-manager=npm\_and\_yarn&previous-version=5.0.10&new-version=5.0.11)](https://docs.github.com/en/github/managing-security-vulnerabilities/about-dependabot-security-updates#about-compatibility-scores) Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting `@dependabot rebase`. [//]: # (dependabot-automerge-start) [//]: # (dependabot-automerge-end) --- Dependabot commands and options You can trigger Dependabot actions by commenting on this PR: - `@dependabot rebase` will rebase this PR - `@dependabot recreate` will recreate this PR, overwriting any edits that have been made to it - `@dependabot merge` will merge this PR after your CI passes on it - `@dependabot squash and merge` will squash and merge this PR after your CI passes on it - `@dependabot cancel merge` will cancel a previously requested merge and block automerging - `@dependabot reopen` will reopen this PR if it is closed - `@dependabot close` will close this PR and stop Dependabot recreating it. 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chore: improve typing in devtools middleware

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dai-shi reviewed Jan 18, 2026

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chore: move checks to typeguard

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grigoriy-reshetniak requested a review from dai-shi January 18, 2026 14:19

dai-shi reviewed Jan 18, 2026

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address review comments

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grigoriy-reshetniak requested a review from dai-shi January 19, 2026 06:39

dai-shi reviewed Jan 19, 2026

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grigoriy-reshetniak requested a review from dai-shi January 19, 2026 13:53

dai-shi requested changes Jan 19, 2026

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change true check to truthy

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grigoriy-reshetniak force-pushed the improve-devtools-typing branch from 5651230 to 634f047 Compare January 19, 2026 15:51

Merge branch 'main' into improve-devtools-typing

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dai-shi approved these changes Jan 20, 2026

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Merge branch 'main' into improve-devtools-typing

ea4ba8d

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dai-shi merged commit 6e026d7 into pmndrs:main Jan 20, 2026
33 checks passed

grigoriy-reshetniak deleted the improve-devtools-typing branch January 20, 2026 04:57

dai-shi added this to the v5.0.11 milestone Feb 1, 2026

	const hasDispatch = (api: unknown): api is WithDispatch =>
	const shouldDispatchFromUs = (api: unknown): api is WithDispatch =>

		typeof (api as WithDispatch).dispatch === 'function' &&
		(api as WithDispatch).dispatchFromDevtools

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grigoriy-reshetniak commented Jan 18, 2026

Summary

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grigoriy-reshetniak commented Jan 20, 2026

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