v0.40.1

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• Fix resolving base config (#​545) d2c5750
• Fix handling of parserOptions option (#​544) e9c96a1

v0.40.0

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Breaking

• XO now enforces that your project is ESM
  If you cannot yet move to ESM, I recommend staying on XO 0.39 for now.
• Require Node.js 12.20 cc06c3c

New rules

• unicorn/prefer-node-protocol
• unicorn/prefer-module
• unicorn/no-document-cookie
• unicorn/numeric-separators-style
• unicorn/prefer-array-flat
• unicorn/prefer-array-flat-map

Meta

• Move from deprecated ESLint.CLIEngine to ESLint (#​534) 0480d80
  This should hopefully resolve a bunch of issues.

v0.39.1

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• Fix a problem with using XO with Prettier fa34c74

v0.39.0

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New rules

• unicorn/no-static-only-class
• unicorn/prefer-array-flat
• unicorn/prefer-switch
• @typescript-eslint/no-unsafe-argument

Breaking

• Remove the esnext option e80c094
• unicorn/prevent-abbreviations rule: Rename options sindresorhus/eslint-plugin-unicorn@cf42cc5
• unicorn/no-keyword-prefix rule: Rename blacklist option to disallowedPrefixes sindresorhus/eslint-plugin-unicorn@91e60d0

Improvements

• Add --print-config flag (#​529) 7b8dc70
• Disable the import/default rule for TypeScript files e3c511b
• Disable the import/export rule for TypeScript files b385bee

v0.38.2

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• Disable the node/file-extension-in-import rule for TypeScript projects (#​523) 1eb8230
  It doesn't work properly with TypeScript projects.

v0.38.1

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• Fix a problem in v0.38.0 8b2fa78

v0.38.0

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New rules

• unicorn/no-new-array
• unicorn/prefer-array-index-of
• unicorn/prefer-regexp-test
• unicorn/no-array-for-each
• unicorn/no-array-push-push
• unicorn/no-this-assignment
• @typescript-eslint/object-curly-spacing

Improvements

• Add auto-fix for fixing file extensions in imports f4f6b39
• Add .mjs and .cjs as default extensions (#​521) 2e05c81
• Allow file extension for import/no-unassigned-import allow list 8156d42

Fixes

• Fix ignored package.json config when using the CLI (#​520) 32bd3b8

v0.37.1

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• Fix TypeScript not supporting extensions f56d90d

v0.37.0

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New rules

• no-unsafe-optional-chaining
• no-useless-backreference
• default-case-last
• no-nonoctal-decimal-escape
• unicorn/prefer-array-some
• unicorn/prefer-default-parameters
• unicorn/no-lonely-if
• unicorn/empty-brace-spaces
• unicorn/prefer-date-now
• @typescript-eslint/non-nullable-type-assertion-style
• @typescript-eslint/no-confusing-void-expression

Renamed rules

Only affects you if you had any of these rules disabled.

• unicorn/no-fn-reference-in-iterator → unicorn/no-array-callback-reference
• unicorn/no-array-instanceof → unicorn/no-instanceof-array
• unicorn/no-reduce → unicorn/no-array-reduce
• unicorn/prefer-dataset → unicorn/prefer-dom-node-dataset
• unicorn/prefer-flat-map → unicorn/prefer-array-flat-map
• unicorn/prefer-replace-all → unicorn/prefer-string-replace-all
• unicorn/prefer-starts-ends-with → unicorn/prefer-string-starts-ends-with
• unicorn/prefer-text-content → unicorn/prefer-dom-node-text-content
• unicorn/prefer-trim-start-end → unicorn/prefer-string-trim-start-end
• unicorn/prefer-event-key → unicorn/prefer-keyboard-event-key
• unicorn/prefer-node-append → unicorn/prefer-dom-node-append
• unicorn/prefer-node-remove → unicorn/prefer-dom-node-remove

Improvements

• Improve ESM compatibility 211f295
• Enforce err → error for variable names d801095
• Enforce some inclusive wording 0ec4b8c

v0.36.1

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• Fix a bug in v0.36 a186078

v0.36.0

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• Add processor option bf6eb25
• Disable warnings when running in a GitHub Actions workflow (#​508) 7731ea1

v0.35.0

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New rules

• @typescript-eslint/no-unnecessary-type-constraint
• @typescript-eslint/space-infix-ops

Improvements

• Allow unassigned stylesheet imports (#​502) b1012d3
• Upgrade dependencies 0555859 6fa99cd

v0.34.2

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• Fix the extensions option (#​503) 35e6336

v0.34.1

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• Disable the unicorn/import-style rule for TypeScript projects 77716e2
  It wants to use import path from 'path'; which is not always possible.

v0.34.0

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New rules

• unicorn/import-style
• unicorn/prefer-math-trunc
• @typescript-eslint/consistent-indexed-object-style
• @typescript-eslint/no-duplicate-imports
• @typescript-eslint/comma-dangle
• @typescript-eslint/no-loop-func
• @typescript-eslint/no-implicit-any-catch

Improvements

• Enable automatic annotations on GitHub Actions (#​497) ba547e7

v0.33.1

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• Fix setting multiple of some CLI flags ead63be

v0.33.0

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New rules

• no-unreachable-loop
• no-promise-executor-return
• no-loss-of-precision
• unicorn/prefer-array-find
• unicorn/no-object-as-default-parameter
• @typescript-eslint/prefer-literal-enum-member
• @typescript-eslint/no-loss-of-precision
• @typescript-eslint/ban-tslint-comment

Improvements

• Respect Prettier’s use of .editorconfig (#​493) f45ab80

v0.32.1

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• Dependency updates

v0.32.0

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• Disable some problematic rules 0dd4a9d
• Add more extensions to import/extensions rule d3abdb6

v0.31.0

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New rules

• unicorn/prefer-optional-catch-binding
• unicorn/no-reduce
• @typescript-eslint/lines-between-class-members
• @typescript-eslint/no-invalid-void-type
• @typescript-eslint/prefer-ts-expect-error
• @typescript-eslint/no-unnecessary-condition
• import/no-anonymous-default-export
• import/no-named-default

Improvements

• Upgrade to ESLint 7
• Add support for scoped shareable configs (#​480) 6a05691

v0.30.0

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New rules

• Add @typescript-eslint/class-literal-property-style rule
• Add @typescript-eslint/prefer-readonly-parameter-types rule
• Add @typescript-eslint/no-base-to-string rule
• Add @typescript-eslint/keyword-spacing rule
• Add @typescript-eslint/method-signature-style rule
• Add @typescript-eslint/prefer-reduce-type-parameter rule
• Add @typescript-eslint/no-floating-promises rule
• Re-enable some disabled rules xojs/eslint-config-xo-typescript@e870168

Fixes

• Lock prettier dependency at 2.0.4 until we can resolve #​466
• Prevent extraneous newline from --stdin --fix (#​460) 07e2762

v0.29.1

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• Add tap-snapshots/*.cjs to default ignore list (#​461) 4783f26
• Temporarily disable the unicorn/string-content rule (#​462) 967927d

v0.29.0

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New rules

• unicorn/prefer-number-properties
• unicorn/prefer-set-has
• @typescript-eslint/class-literal-property-style
• @typescript-eslint/no-unsafe-return
• @typescript-eslint/no-unsafe-member-access
• @typescript-eslint/no-unsafe-call
• @typescript-eslint/prefer-readonly-parameter-types
• @typescript-eslint/no-base-to-string

Improvements

• Upgrade to Prettier 2 (#​458) e05efc3
• Allow nodeVersion in XO config to override engines.node (#​457) f20f6d2
• Add ignore option to expiring-todo-comment rule

v0.28.3

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• Support semicolon option with TypeScript (#​446) c47a0c6
• Add TS extends after base XO extends and before user extends (#​453) a4625a7

v0.28.2

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• Set indent rule for TS files too (#​451) 41b1bd7
• Fix compatibility with latest TypeScript-ESLint version (#​452) 28902f0

v0.28.1

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• Add xo-typescript and prettier/@​typescript-eslint before user extends (#​442) 6c57ff7
• Change XO cache path to avoid conflicts when upgrading (#​443) fc30597

v0.28.0

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New rules

• Add unicorn/string-content rule (#​439) 5a22b77
• Add unicorn/prevent-abbreviations rule ba4efc9
  This rule enforces more readable code by preventing the use of certain abbreviations in favor of the full word. Not everyone knows all abbreviations. Saving a few characters are not worth making your code less readable. List of abbreviations XO prevents.

Improvements

• Add webpack option (#​375) f656ee3
• Get extensions and ignores from config files (#​436) 0d63c64

v0.27.2

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• Sort file paths before generating unique cache key (#​432) 1807537

v0.27.1

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• Various fixes to TypeScript integration (#​431) 0ea5dbb

Important: We changed the cache structure, so you'll need to delete node_modules/.cache/xo:

$ rm node_modules/.cache/xo

v0.27.0

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• Add TypeScript support (#​426) b0dfcbd
  You can now lint TypeScript projects without any extra config. You can also lint d.ts files in JS projects. Read more.
• Find XO config based on linted file path (#​425) e0f81a7
• Fix overrides handling for extends, envs, globals, plugins (#​429) 4cefdbc
• Add node/no-unsupported-features rules (#​341) 2297c07
• Improve import/no-unassigned-import settings (#​430) 0c78113

v0.26.1

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• Use new eslint-config-prettier override (#​422) 9fbdb97

v0.26.0

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Breaking

• Require Node.js 10 d7fa875
• Move $ xo --init to $ npm init xo 6463dfe

New rules

20 new rules 👌

ESLint

• default-param-last
• function-call-argument-newline
• grouped-accessor-pairs
• no-constructor-return
• no-dupe-else-if
• no-import-assign
• no-setter-return
• no-useless-catch
• prefer-exponentiation-operator
• prefer-named-capture-group
• prefer-object-spread
• prefer-regex-literals

Unicorn

• unicorn/prefer-modern-dom-apis
• unicorn/prefer-negative-index
• unicorn/prefer-replace-all
• unicorn/prefer-string-slice
• unicorn/prefer-trim-start-end

Other

• node/prefer-global/url-search-params
• node/prefer-global/url
• promise/prefer-await-to-then

Enhancements

• Set the es2020 environment by default eb5ea2c

Fixes

• Fix compatibility with being run in a child process (#​405) 08af7c1

v0.25.4

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• Temporarily disable the import/order rule 776927f

v0.25.3

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• Enable unicorn/prefer-flat-map only for Node.js >=11 (#​403) 80c592e

v0.25.2

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• Disable no-nested-ternary rule when Prettier is used (#​402) 537ef66

v0.25.1

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• Don't report normal TODO comments as errors 4378e83

v0.25.0

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Breaking

• Require Node.js 8 8a213ef
• Upgrade to ESLint 6 698b043
• Enforce using the .json extension for JSON files in imports 7e56730

New rules

• Add prefer-named-capture-group rule (for Node.js >=10 target) 21e7b57
• Add default-param-last rule
• Add prefer-regex-literals rule
• Add no-import-assign rule
• Add unicorn/expiring-todo-comments rule
• Add unicorn/no-nested-ternary rule
• Add unicorn/prefer-reflect-apply rule
• Add unicorn/prefer-string-slice rule
• Add unicorn/prefer-dataset rule
• Add unicorn/no-for-loop rule
• Add unicorn/no-zero-fractions rule
• Add unicorn/prefer-includes rule
• Add unicorn/prefer-text-content rule
• Add unicorn/prefer-node-remove rule
• Add unicorn/prefer-event-key rule
• Add unicorn/prefer-flat-map rule
• Add node/prefer-promises/fs rule a3d74a6
• Add node/prefer-promises/dns rule 8f8fc94

Enhancements

• Respect .eslintignore (#​377) f6bf4c0
• Turn all paths cwd-relative before linting (#​372) 3033fcd
• Add option to import/no-useless-path-segments rule 8d6c5c5
• Add tap-snapshots/*.js to default ignore list (#​385) b73b11b
• Make --stdin --fix always return the code even if nothing was fixed (#​383) ec51d18

v0.24.0

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Highlights

• You can now click/Command-click the rule IDs in the output to open the rule's docs. Preview. (Only in supported terminals) sindresorhus/eslint-formatter-pretty@7606f98
• Move default ESLint cache to node_modules/.cache/xo. (#​351) d1fd3e1
• Support parsing ES2019 61f9582
• Drop support for Babel 6 in the import/no-unassigned-import rule dd2c015

New rules

• padding-line-between-statements
• no-useless-catch
• unicorn/prefer-query-selector
• unicorn/prefer-node-append
• unicorn/no-unreadable-array-destructuring
• unicorn/no-console-spaces
• eslint-comments/disable-enable-pair
• eslint-comments/no-aggregating-enable
• eslint-comments/no-duplicate-disable
• eslint-comments/no-unused-disable
• eslint-comments/no-unused-enable
• node/prefer-global/buffer
• node/prefer-global/console
• node/prefer-global/process
• node/prefer-global/text-decoder (When targeting Node.js 11)
• node/prefer-global/text-encoder (When targeting Node.js 11)
• node/prefer-global/url-search-params (When targeting Node.js 10)
• node/prefer-global/url (When targeting Node.js 10)

All changes

v0.23.0

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Highlights

• In v0.22.0, we added support for .ts and .tsx extensions by default. This caused a lot of problems for non-TS projects, so it has been reverted pending a better solution.
• The quotes rule is now set to disallow using template literals when you're not using any interpolation. xojs/eslint-config-xo@ea693f3
• Removed the no-use-before-define rule. It has too many false-positives. xojs/eslint-config-xo@1257597

New rules

• require-await
• unicorn/prefer-exponentiation-operator
• unicorn/catch-error-name (See this thread if you're wondering why error is preferred over err) (Sorry about the churn, but this is an important milestone towards more readable code. Code is written once but read many times. We should optimize for the latter.)

All changes

v0.22.0

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Highlights

• Upgraded to ESLint 5.
• Removed some patterns from the list of default ignores. They were too opinionated. 00d6b7c 8e4f435
  - fixture{-*,}.{js,jsx}
  - fixture{s,}/**
  - {test,tests,spec,__tests__}/fixture{s,}/**
  - **/bundle.js
• Added support for TypeScript and documented usage with Flow. 957b0d9
• Now respects nodeVersion option set in an override block. 98dee9a
• Fixed the CLI's --space option parsing. f76c901

New rules

• no-misleading-character-class
• require-atomic-updates
• no-async-promise-executor
• ava/no-import-test-file

All changes

v0.21.1

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Fix space/useTabs conflict message with Prettier. 36f7f38

v0.21.0

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Highlights

• Dropped support for Node.js 4 and 5 as they reached end of life. Node.js 6 is the minimum required version.
• Upgrade to Prettier 1.12.1.
• The default value for trailingComma Prettier option is now none. f67ff58
• Disable unicorn/number-literal-case when using Prettier to avoid conflict. 4fd6991
• Ignore prettier-ignore comments in capitalized-comments rule. xojs/eslint-config-xo@6e417ff
• Fix missed detection of incorrect indentation with indent rule. xojs/eslint-config-xo@145993e
• Allow named function in prefer-arrow-callback. xojs/eslint-config-xo@bda02cb

New rules

• valid-jsdoc
• promise/no-new-statics
• promise/valid-params
• import/no-self-import
• import/no-useless-path-segments

Removed rules

• import/prefer-default-export

v0.20.3

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v0.20.2

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v0.20.1

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v0.20.0

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This release is way overdue, so glad to finally have it out! It includes a major ESLint upgrade, huge performance improvements, Prettier support, lots of new rules, and bug fixes.

The project was recently moved to a GitHub organization, and we got a new team member, Pierre Vanduynslager ✨

We now also have configs for TypeScript (using tslint) and CSS & Sass (using stylelint). And don't forget, we already have a config for React.

Many of the new rules in this release are from the eslint-plugin-unicorn plugin, which could use some contributions.

Highlights

• Upgraded to ESLint 4. a11e288
• Added optional Prettier support. fd89175
• Improved performance. 552cbb1
• Now toggles rules based on the engines field in package.json. 0d18368
• Disabled linebreak-style rule on Windows. xojs/eslint-config-xo@3f81796
• Made the spaced-comment rule more lenient. xojs/eslint-config-xo@e4f1f36
• Now allows _ as argument name in the no-unused-vars rule. xojs/eslint-config-xo@dda366b
• The --open flag now opens errors first and not warnings. 6f6a606
• Removed deprecated --compact CLI flag. 652a6e5
• Excluded babel-register and babel-polyfill from the no-unassigned-import rule. 70d6ab4
• Sets ecmaVersion to 2018. 9859dfb

New rules

22 new rules!

• semi-style xojs/eslint-config-xo@0b1680e
• for-direction xojs/eslint-config-xo@c957c7f
• switch-colon-spacing xojs/eslint-config-xo@c1c8fc7
• no-buffer-constructor xojs/eslint-config-xo@ee366cb
• getter-return xojs/eslint-config-xo@40e1442
• function-paren-newline xojs/eslint-config-xo@9e90fdc
• lines-between-class-members xojs/eslint-config-xo@c7f63cd
• array-bracket-newline xojs/eslint-config-xo@e2f3748
• unicorn/prefer-add-event-listener
• unicorn/prefer-spread rule
• unicorn/no-unsafe-regex
• unicorn/error-message
• unicorn/import-index
• unicorn/new-for-builtins
• unicorn/regex-shorthand
• unicorn/escape-case
• unicorn/no-hex-escape
• promise/no-return-wrap 4273f8a
• promise/no-return-in-finally 4273f8a
• node/no-unpublished-bin 16fb8e2
• node/process-exit-as-throw 16fb8e2
• node/no-deprecated-api 16fb8e2

All changes

Why is this not 0.19.0? That version got tainted by an incorrect publish a long time ago.

v0.19.0

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