ESLint v8.57.0 released

Highlights

This release backports from v9.x to v8.x two new features and several bug fixes related to the flat config system to help plugins, integrations and users migrate to flat config ahead of the final v9.0.0 release.

Support for eslint.config.mjs and eslint.config.cjs

This release introduces support for eslint.config.mjs and eslint.config.cjs configuration files to v8.x in addition to eslint.config.js, making it easier to use the module format you’d prefer regardless of the module format of the containing package.

New API loadESLint()

ESLint now exports a new function loadESLint() from its main entry point. Integrations can use this function to get either the FlatESLint class (ESLint class in v9.x) or the ESLint class (LegacyESLint class in v9.x) and thus easily swap between flat config and eslintrc APIs.

Features

• 1120b9b feat: Add loadESLint() API method for v8 (#18098) (Nicholas C. Zakas)
• dca7d0f feat: Enable eslint.config.mjs and eslint.config.cjs (#18066) (Nitin Kumar)

Bug Fixes

• 2196d97 fix: handle absolute file paths in FlatRuleTester (#18064) (Nitin Kumar)
• 69dd1d1 fix: Ensure config keys are printed for config errors (#18067) (Nitin Kumar)
• 9852a31 fix: deep merge behavior in flat config (#18065) (Nitin Kumar)
• 4c7e9b0 fix: allow circular references in config (#18056) (Milos Djermanovic)

Documentation

• 84922d0 docs: Show prerelease version in dropdown (#18139) (Nicholas C. Zakas)
• 5b8c363 docs: Switch to Ethical Ads (#18117) (Milos Djermanovic)
• 77dbfd9 docs: show NEXT in version selectors (#18052) (Milos Djermanovic)

Chores

• 1813aec chore: upgrade @eslint/js@8.57.0 (#18143) (Milos Djermanovic)
• 5c356bb chore: package.json update for @eslint/js release (Jenkins)
• f4a1fe2 test: add more tests for ignoring files and directories (#18068) (Nitin Kumar)
• 42c0aef ci: Enable CI for v8.x branch (#18047) (Milos Djermanovic)