# Jotai v2.20.0

- Product: Jotai (https://whatsnew.fyi/product/jotai)
- Vendor: Poimandres
- Date: 2026-05-06
- Version: v2.20.0
- Original notes: https://github.com/pmndrs/jotai/releases/tag/v2.20.0
- Permalink: https://whatsnew.fyi/product/jotai/releases/v2.20.0

What's New is an index, not a publisher: every entry below links to the vendor's own release notes, which are the authoritative source. Entries are labelled where they are hand-curated sample data, pre-releases, or drawn from a secondary source such as a developer blog.

Reuse: the summaries, labels and curation here are © What's New. Quote freely with attribution and a link back; wholesale republication of the corpus is not permitted — terms: https://whatsnew.fyi/terms. The vendors' own release notes remain their publishers'.

---

- **changed** — Avoid getInternalBuildingBlock function in internals
- **changed** — Refactor Rev3 type narrowing for onMount hooks
- **fixed** — Guard atomOnInit hook with hasOnInit
- **changed** — Use lazy hooks in ensureAtomState for new atom state

This release improves performance in high-throughput scenarios. Huge kudos to @dmaskasky!

##### What's Changed
* breaking(internals): avoid getInternalBuildingBlock function by @dai-shi in https://github.com/pmndrs/jotai/pull/3293
* refactor(internals): Rev3 type narrowing for onMount hooks by @dmaskasky in https://github.com/pmndrs/jotai/pull/3311
* fix(internals): guard atomOnInit hook with hasOnInit by @dmaskasky in https://github.com/pmndrs/jotai/pull/3312
* refactor(internals): lazy hooks in ensureAtomState for new atom state by @dmaskasky in https://github.com/pmndrs/jotai/pull/3313


**Full Changelog**: https://github.com/pmndrs/jotai/compare/v2.19.1...v2.20.0