immer

Release notes

• breaking

  Immer 10 only supports modern browsers, that have support for Proxy, Reflect, Symbol and Map and Set.

• breaking

  There is no longer a UMD build exposed (thanks Mark Erikson for modernizing the build setup in #1032!

• breaking

  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. Thanks hrsh7th for implementing it in #941!

• breaking

  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 leveraging createDraft and finishDraft.

• breaking

  ES5 mode (for legacy browsers) has been dropped. If your project relies on enableES5(), you SHOULD NOT upgrade Immer. enableES5 has been removed.

• breaking

  produce is no longer exposed as the default export. This improves eco system compatibility, and makes sure that there is only one correct way of doing things

• breaking

  enableAllPlugins has been removed, use enablePatches(); enableMapSet() instead

• breaking

  Shortening the length of a JSON array now results in delete patches, rather than a mutation of the length property, in accordance with JSON spec. Thanks kshramt 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 just produce has remained roughly the same at 3.3 KB.

For more details, see #1015

Migration steps

1. If you have any enableES5() call, don't migrate

2. When using getters/ setters icmw plain objects, call useStrictShallowCopy(true) at startup

3. Replace all default imports: Replace import produce from "immer" with import {produce} from "immer"

4. Replace all calls to enableAllPlugins() with enablePatches(); enableMapSet(); to be more specific and smoothen future migrations.

5. If any producer returned a Promise, refactor it to leverage createDraft instead. Roughly:

const newState = await produce(oldState, recipe)

// becomes
const draft  = createDraft(oldState)
await recipe(draft)
const newState = finishDraft(draft)