ESLint v9.21.0 released

Highlights

--ext CLI Option

This version of ESLint reintroduces the command line option --ext to allow linting files with a particular extension. The --ext option has always been available in the legacy “eslintc” configuration system, but it was eliminated in the new configuration system because its functionality can be easily achieved through files patterns. For example, specifying files: ["**/*.ts"] in a configuration object will lint all files that have the .ts extension. files patterns are useful to lint files with extensions other than .js, .mjs or .cjs, but they require a configuration file. In order to lint files with arbitrary extensions without a configuration file, the --ext option can now be used in the command line like this:

npx eslint --no-config-lookup --rule '{"no-unused-vars": "error"}' --ext '.jsx'

See the CLI documentation for further information.

New Metadata for Deprecated Rules

ESLint v9.21.0 extends the format of rule metadata to better annotate deprecated rules, providing more detailed information. This includes the specific version of a plugin in which a rule was deprecated, as well as links to alternative rules and plugins. Learn more.

Features

• 418717f feat: introduce new deprecated types for rules (#19238) (fnx)
• 5c5b802 feat: Add --ext CLI option (#19405) (Milos Djermanovic)

Bug Fixes

• db5340d fix: update missing plugin message template (#19445) (Milos Djermanovic)
• d8ffdd4 fix: do not exit process on rule crash (#19436) (Francesco Trotta)

Documentation

• c5561ea docs: Update README (GitHub Actions Bot)
• 80b0485 docs: replace var with let and const in rule example (#19434) (Tanuj Kanti)
• f67d5e8 docs: Update README (GitHub Actions Bot)
• 75afc61 docs: Update README (GitHub Actions Bot)
• 0636cab docs: Update Eleventy from v2 to v3 (#19415) (Amaresh S M)
• dd7d930 docs: Update README (GitHub Actions Bot)

Chores

• a8c9a9f chore: update @eslint/eslintrc and @eslint/js (#19453) (Francesco Trotta)
• 265e0cf chore: package.json update for @eslint/js release (Jenkins)
• 3401b85 test: add test for Rule.ReportDescriptor type (#19449) (Francesco Trotta)
• e497aa7 chore: update rewrite dependencies (#19448) (Francesco Trotta)
• dab5478 chore: better error message for missing plugin in config (#19402) (Tanuj Kanti)
• ebfe2eb chore: set js language for bug report issue config block (#19439) (Josh Goldberg ✨)
• 5fd211d test: processors can return subpaths (#19425) (Milos Djermanovic)