10.2.0 (2025-10-25)

Features

• Optimize Immer performance where possible, introducesetUseStrictIteration (#1164) (e1996ce)

10.1.3 (2025-09-01)

Bug Fixes

• Mark exports as pure, for better tree-shakability (#1124) (85faaa2)

10.1.2 (2025-09-01)

Bug Fixes

• non-enumerable (immutable) methods on Map/Set (#1069) (aa24400)
• Update package.json exports for react-native (#1159) (b2fcc66)

10.1.1 (2024-04-27)

Bug Fixes

• export lost types (#1116) (5a8f6e7)
• MakeapplyPatches to acceptreadonly Patch[] (#1094) (4da2e0d)

10.1.0 (2024-04-27)

Features

• performance: Make non-strict mode faster for classes. Addresses#1071 (53e3203). Immer 10.x solved slow iteration for plain JS objects. This update applies the same handling to class instances. In cases this makes class instance handling 3 times faster. Note that this slightly modifies the behavior of Immer with classes in obscure corner cases, in ways that match current documentation, but do not match previous behavior. If you run into issues with this release icmw. class instances, usesetUseStrictShallowCopy("class_only") to revert to the old behavior. For more details seehttps://immerjs.github.io/immer/complex-objects#semantics-in-detail

10.0.4 (2024-03-09)

Bug Fixes

• Fix handling of Symbol and non-enumerable properties in finalization / freeze. Fixes#1096,#1087,#1091 (#1105)) (8949a3e)

10.0.3 (2023-10-02)

Bug Fixes

• don't use.mjs file for react-native, which isn't supported by default. Fixes#1058#1065 (#1075) (f6736a4)

10.0.2 (2023-05-09)

Bug Fixes

• exportObjectish type (#1043) (75e004d)
• Move index.js.flow from dist/ -> dist/cjs/ to match index.js (#1038) (a3b5603)

10.0.1 (2023-04-17)

Bug Fixes

• production bundle was loaded incorrectly, fixes#1037 (707e72b)

10.0.0 (2023-04-17)

Release notes

• [breaking change] Immer 10 only supports modern browsers, that have support forProxy,Reflect,Symbol andMap andSet.
• [breaking change] There is no longer a UMD build exposed (thanksMark Erikson for modernizing the build setup in#1032!
• [breaking change] getters and setters are ignored by default on plain object, as this is a very uncommon case and provides a significant performance boost (ca 33%, but depends a lot on the scenario). Fixes#867,#1012. Thankshrsh7th for implementing it in#941!
• [breaking change] Promise based reducers are no longer supported. Conceptually it is an anti pattern to hold on to drafts over time. If needed the old behavior can still be achieved by leveragingcreateDraft andfinishDraft.
• [breaking change] ES5 mode (for legacy browsers) has been dropped. If your project relies onenableES5(), you SHOULD NOT upgrade Immer.enableES5 has been removed.
• [breaking change]produce is no longer exposed as thedefault export. This improves eco system compatibility, and makes sure that there is only one correct way of doing things
• [breaking change]enableAllPlugins has been removed, useenablePatches(); enableMapSet() instead
• [breaking change] shortening the length of a JSON array now results in delete patches, rather than a mutation of thelength property, in accordance with JSON spec. Thankskshramt for implementing this in#964!
• Immer is now an ESM package that can be directly imported into the browser. CJS should still work, UMD support has been removed.

Overall, there is a rough performance increase of 33% for Immer (and in some cases significantly higher), and the (non gzipped) bundle size has reduced from 16 to 11.5 KB, while the the minimal gzipped import of justproduce has remained roughly the same at 3.3 KB.

For more details, see#1015

Migration steps

1. If you have anyenableES5() call, don't migrate
2. When using getters/ setters icmw plain objects, calluseStrictShallowCopy(true) at startup
3. Replace all default imports: Replaceimport produce from "immer" withimport {produce} from "immer"
4. Replace all calls toenableAllPlugins() withenablePatches(); enableMapSet(); to be more specific and smoothen future migrations.
5. If any producer returned a Promise, refactor it to leveragecreateDraft instead. Roughly:

constnewState=awaitproduce(oldState,recipe)// becomesconstdraft=createDraft(oldState)awaitrecipe(draft)constnewState=finishDraft(draft)