# MobX 6.3.3

- Product: MobX (https://whatsnew.fyi/product/mobx)
- Vendor: MobX
- Date: 2021-08-31
- Version: 6.3.3
- Original notes: https://github.com/mobxjs/mobx/releases/tag/mobx%406.3.3
- Permalink: https://whatsnew.fyi/product/mobx/releases/6.3.3

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'.

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- **changed** — trace() now logs when computed becomes suspended
- **changed** — requiresReaction warns instead of throwing
- **fixed** — Create WHEN_TIMEOUT error earlier to capture useful stack
- **added** — Polyfill Object.is for old/unsupported browsers
- **changed** — Give proper typing to opts.equals of reaction
- **fixed** — Remove duplicate global property check

###### Patch Changes

-   [`d78a1592`](https://github.com/mobxjs/mobx/commit/d78a15929052b96698b3355a0b4c8335750422db) [#2902](https://github.com/mobxjs/mobx/pull/2902) Thanks [@z3rog](https://github.com/z3rog)! - chore: observable use internal constants


-   [`db21d85f`](https://github.com/mobxjs/mobx/commit/db21d85fcd41c6c142998f53e722ee0a0e9b5c18) [#2998](https://github.com/mobxjs/mobx/pull/2998) Thanks [@urugator](https://github.com/urugator)! - `trace()`: log when computed becomes suspended
    `requiresReaction` warns instead of throwing


-   [`b9fa119c`](https://github.com/mobxjs/mobx/commit/b9fa119c90e23d4b327763189f24c00be2fb2c26) [#3056](https://github.com/mobxjs/mobx/pull/3056) Thanks [@upsuper](https://github.com/upsuper)! - Create WHEN_TIMEOUT error earlier to capture useful stack


-   [`99491ec2`](https://github.com/mobxjs/mobx/commit/99491ec2d315a3a01cdbe40d9a24d920a09cbd0e) [#2972](https://github.com/mobxjs/mobx/pull/2972) Thanks [@kk-gjyang](https://github.com/kk-gjyang)! - Polyfill `Object.is` for old/unsupported browsers


-   [`0d28db8a`](https://github.com/mobxjs/mobx/commit/0d28db8a0ba99f5cce744bb83b5bd88ec45a7e41) [#2927](https://github.com/mobxjs/mobx/pull/2927) Thanks [@upsuper](https://github.com/upsuper)! - Give proper typing to opts.equals of reaction


-   [`c6dc925c`](https://github.com/mobxjs/mobx/commit/c6dc925c6cf7eeff9237ee07c55927a7bbc14cb7) [#2985](https://github.com/mobxjs/mobx/pull/2985) Thanks [@fecqs](https://github.com/fecqs)! - Remove duplicate global property check