# What changed in jest-util

> 10 changes in jest-util 30 from its official release notes, upgrade guides and advisories: 1 deprecations, 1 new APIs and options. Each one cited. Sources checked 2026-10-23. HTML: https://unstale.sh/npm/jest-util/

To see which of these apply to a repository, run `npx @unstale/cli init` in it.

## jest-util 30

### Deprecations

- The JEST-01 deprecation warning now names this option and links to its documentation, which describes the option's modes. (30.5.1) — [release notes](https://github.com/jestjs/jest/blob/15c3d19dc2803892a3d0b08b863dee85aea48215/CHANGELOG.md#3051)

### New APIs and options

- Adds the isError helper. (30.4.0) — [release notes](https://github.com/jestjs/jest/blob/15c3d19dc2803892a3d0b08b863dee85aea48215/CHANGELOG.md#3040)

### Performance

- Global variables are cleaned up on environment teardown to reduce memory leaks. (30.0.0) — [release notes](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md)

### Fixes and other changes

- Only warn about a conflicting globalsCleanup mode when one was explicitly configured, and follow the mode actually in effect. (30.5.0) — [release notes](https://github.com/jestjs/jest/blob/15c3d19dc2803892a3d0b08b863dee85aea48215/CHANGELOG.md#3050)
- Matchers no longer reuse cached results compiled with different picomatch options, and the dot: true default is preserved when dot is undefined. (30.5.0) — [release notes](https://github.com/jestjs/jest/blob/15c3d19dc2803892a3d0b08b863dee85aea48215/CHANGELOG.md#3050)
- Environment setup no longer resolves lazy globals, preventing Node 26 builtin module globals and their deprecation warnings from loading for every test file. (30.5.0) — [release notes](https://github.com/jestjs/jest/blob/15c3d19dc2803892a3d0b08b863dee85aea48215/CHANGELOG.md#3050)
- Reverted node: protocol imports to restore webpack/browser-bundle compatibility. (30.5.0) — [release notes](https://github.com/jestjs/jest/blob/15c3d19dc2803892a3d0b08b863dee85aea48215/CHANGELOG.md#3050)
- Ensure process.features.require_module is false. (30.3.0) — [release notes](https://github.com/jestjs/jest/blob/15c3d19dc2803892a3d0b08b863dee85aea48215/CHANGELOG.md#3030)
- Fixed `isInteractive` to work in a browser. (30.0.0) — [release notes](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md)
- Always load `mjs` files with `import`. (30.0.0) — [release notes](https://github.com/jestjs/jest/blob/HEAD/CHANGELOG.md)