eslint-plugin-unicorn

# eslint-plugin-unicorn [![Coverage Status](https://codecov.io/gh/sindresorhus/eslint-plugin-unicorn/branch/main/graph/badge.svg)](https://codecov.io/gh/sindresorhus/eslint-plugin-unicorn/branch/main) <img src="https://cloud.githubusercontent.com/assets/170270/18659176/1cc373d0-7f33-11e6-890f-0ba35362ee7e.jpg" width="180" align="right"> > Various awesome ESLint rules You might want to check out [XO](https://github.com/xojs/xo), which includes this plugin. [**Propose or contribute a new rule ➡**](.github/contributing.md) ## Install ```console $ npm install --save-dev eslint eslint-plugin-unicorn ``` ## Usage Configure it in `package.json`. ```json { "name": "my-awesome-project", "eslintConfig": { "env": { "es6": true }, "parserOptions": { "ecmaVersion": 2021, "sourceType": "module" }, "plugins": [ "unicorn" ], "rules": { "unicorn/better-regex": "error", "unicorn/catch-error-name": "error", "unicorn/consistent-destructuring": "error", "unicorn/consistent-function-scoping": "error", "unicorn/custom-error-definition": "off", "unicorn/empty-brace-spaces": "error", "unicorn/error-message": "error", "unicorn/escape-case": "error", "unicorn/expiring-todo-comments": "error", "unicorn/explicit-length-check": "error", "unicorn/filename-case": "error", "unicorn/import-index": "off", "unicorn/import-style": "error", "unicorn/new-for-builtins": "error", "unicorn/no-abusive-eslint-disable": "error", "unicorn/no-array-callback-reference": "error", "unicorn/no-array-for-each": "error", "unicorn/no-array-push-push": "error", "unicorn/no-array-reduce": "error", "unicorn/no-console-spaces": "error", "unicorn/no-for-loop": "error", "unicorn/no-hex-escape": "error", "unicorn/no-instanceof-array": "error", "unicorn/no-keyword-prefix": "off", "unicorn/no-lonely-if": "error", "no-nested-ternary": "off", "unicorn/no-nested-ternary": "error", "unicorn/no-new-array": "error", "unicorn/no-new-buffer": "error", "unicorn/no-null": "error", "unicorn/no-object-as-default-parameter": "error", "unicorn/no-process-exit": "error", "unicorn/no-this-assignment": "error", "unicorn/no-unreadable-array-destructuring": "error", "unicorn/no-unsafe-regex": "off", "unicorn/no-unused-properties": "off", "unicorn/no-useless-undefined": "error", "unicorn/no-zero-fractions": "error", "unicorn/number-literal-case": "error", "unicorn/numeric-separators-style": "off", "unicorn/prefer-add-event-listener": "error", "unicorn/prefer-array-find": "error", "unicorn/prefer-array-flat-map": "error", "unicorn/prefer-array-index-of": "error", "unicorn/prefer-array-some": "error", "unicorn/prefer-date-now": "error", "unicorn/prefer-default-parameters": "error", "unicorn/prefer-dom-node-append": "error", "unicorn/prefer-dom-node-dataset": "error", "unicorn/prefer-dom-node-remove": "error", "unicorn/prefer-dom-node-text-content": "error", "unicorn/prefer-includes": "error", "unicorn/prefer-keyboard-event-key": "error", "unicorn/prefer-math-trunc": "error", "unicorn/prefer-modern-dom-apis": "error", "unicorn/prefer-negative-index": "error", "unicorn/prefer-number-properties": "error", "unicorn/prefer-optional-catch-binding": "error", "unicorn/prefer-query-selector": "error", "unicorn/prefer-reflect-apply": "error", "unicorn/prefer-regexp-test": "error", "unicorn/prefer-set-has": "error", "unicorn/prefer-spread": "error", "unicorn/prefer-string-replace-all": "off", "unicorn/prefer-string-slice": "error", "unicorn/prefer-string-starts-ends-with": "error", "unicorn/prefer-string-trim-start-end": "error", "unicorn/prefer-ternary": "off", "unicorn/prefer-type-error": "error", "unicorn/prevent-abbreviations": "error", "unicorn/string-content": "off", "unicorn/throw-new-error": "error" } } } ``` ## Rules - [better-regex](docs/rules/better-regex.md) - Improve regexes by making them shorter, consistent, and safer. *(fixable)* - [catch-error-name](docs/rules/catch-error-name.md) - Enforce a specific parameter name in catch clauses. *(fixable)* - [consistent-destructuring](docs/rules/consistent-destructuring.md) - Use destructured variables over properties. *(partly fixable)* - [consistent-function-scoping](docs/rules/consistent-function-scoping.md) - Move function definitions to the highest possible scope. - [custom-error-definition](docs/rules/custom-error-definition.md) - Enforce correct `Error` subclassing. *(fixable)* - [empty-brace-spaces](docs/rules/empty-brace-spaces.md) - Enforce no spaces between braces. *(fixable)* - [error-message](docs/rules/error-message.md) - Enforce passing a `message` value when creating a built-in error. - [escape-case](docs/rules/escape-case.md) - Require escape sequences to use uppercase values. *(fixable)* - [expiring-todo-comments](docs/rules/expiring-todo-comments.md) - Add expiration conditions to TODO comments. - [explicit-length-check](docs/rules/explicit-length-check.md) - Enforce explicitly comparing the `length` property of a value. *(partly fixable)* - [filename-case](docs/rules/filename-case.md) - Enforce a case style for filenames. - [import-index](docs/rules/import-index.md) - Enforce importing index files with `.`. *(fixable)* - [import-style](docs/rules/import-style.md) - Enforce specific import styles per module. - [new-for-builtins](docs/rules/new-for-builtins.md) - Enforce the use of `new` for all builtins, except `String`, `Number`, `Boolean`, `Symbol` and `BigInt`. *(partly fixable)* - [no-abusive-eslint-disable](docs/rules/no-abusive-eslint-disable.md) - Enforce specifying rules to disable in `eslint-disable` comments. - [no-array-callback-reference](docs/rules/no-array-callback-reference.md) - Prevent passing a function reference directly to iterator methods. - [no-array-for-each](docs/rules/no-array-for-each.md) - Prefer `for…of` over `Array#forEach(…)`. *(partly fixable)* - [no-array-push-push](docs/rules/no-array-push-push.md) - Enforce combining multiple `Array#push()` into one call. *(partly fixable)* - [no-array-reduce](docs/rules/no-array-reduce.md) - Disallow `Array#reduce()` and `Array#reduceRight()`. - [no-console-spaces](docs/rules/no-console-spaces.md) - Do not use leading/trailing space between `console.log` parameters. *(fixable)* - [no-for-loop](docs/rules/no-for-loop.md) - Do not use a `for` loop that can be replaced with a `for-of` loop. *(partly fixable)* - [no-hex-escape](docs/rules/no-hex-escape.md) - Enforce the use of Unicode escapes instead of hexadecimal escapes. *(fixable)* - [no-instanceof-array](docs/rules/no-instanceof-array.md) - Require `Array.isArray()` instead of `instanceof Array`. *(fixable)* - [no-keyword-prefix](docs/rules/no-keyword-prefix.md) - Disallow identifiers starting with `new` or `class`. - [no-lonely-if](docs/rules/no-lonely-if.md) - Disallow `if` statements as the only statement in `if` blocks without `else`. *(fixable)* - [no-nested-ternary](docs/rules/no-nested-ternary.md) - Disallow nested ternary expressions. *(partly fixable)* - [no-new-array](docs/rules/no-new-array.md) - Disallow `new Array()`. *(partly fixable)* - [no-new-buffer](docs/rules/no-new-buffer.md) - Enforce the use of `Buffer.from()` and `Buffer.alloc()` instead of the deprecated `new Buffer()`. *(partly fixable)* - [no-null](docs/rules/no-null.md) - Disallow the use of the `null` literal. - [no-object-as-default-parameter](docs/rules/no-object-as-default-parameter.md) - Disallow the use of objects as default parameters. - [no-process-exit](docs/rules/no-process-exit.md) - Disallow `process.exit()`. - [no-this-assignment](docs/rules/no-this-assignment.md) - Disallow assigning `this` to a variable. - [no-unreadable-array-destructuring](docs/rules/no-unreadable-array-destructuring.md) - Disallow unreadable array destructuring. *(partly fixable)* - [no-unsafe-regex](docs/rules/no-unsafe-regex.md) - Disallow unsafe regular expressions. - [no-unused-properties](docs/rules/no-unused-properties.md) - Disallow unused object properties. - [no-useless-undefined](docs/rules/no-useless-undefined.md) - Disallow useless `undefined`. *(fixable)* - [no-zero-fractions](docs/rules/no-zero-fractions.md) - Disallow number literals with zero fractions or dangling dots. *(fixable)* - [number-literal-case](docs/rules/number-literal-case.md) - Enforce proper case for numeric literals. *(fixable)* - [numeric-separators-style](docs/rules/numeric-separators-style.md) - Enforce the style of numeric separators by correctly grouping digits. *(fixable)* - [prefer-add-event-listener](docs/rules/prefer-add-event-listener.md) - Prefer `.addEventListener()` and `.removeEventListener()` over `on`-functions. *(partly fixable)* - [prefer-array-find](docs/rules/prefer-array-find.md) - Prefer `.find(…)` over the first element from `.filter(…)`. *(partly fixable)* - [prefer-array-flat-map](docs/rules/prefer-array-flat-map.md) - Prefer `.flatMap(…)` over `.map(…).flat()`. *(fixable)* - [prefer-array-index-of](docs/rules/prefer-array-index-of.md) - Prefer `Array#indexOf()` over `Array#findIndex()` when looking for the index of an item. *(partly fixable)* - [prefer-array-some](docs/rules/prefer-array-some.md) - Prefer `.some(…)` over `.find(…)`. - [prefer-date-now](docs/rules/prefer-date-now.md) - Prefer `Date.now()` to get the number of milliseconds since the Unix Epoch. *(fixable)* - [prefer-default-parameters](docs/rules/prefer-default-parameters.md) - Prefer default parameters over reassignment. *(fixable)* - [prefer-dom-node-append](docs/rules/prefer-dom-node-append.md) - Prefer `Node#append()` over `Node#appendChild()`. *(fixable)* - [prefer-dom-node-dataset](docs/rules/prefer-dom-node-dataset.md) - Prefer using `.dataset` on DOM elements over `.setAttribute(…)`. *(fixable)* - [prefer-dom-node-remove](docs/rules/prefer-dom-node-remove.md) - Prefer `childNode.remove()` over `parentNode.removeChild(childNode)`. *(fixable)* - [prefer-dom-node-text-content](docs/rules/prefer-dom-node-text-content.md) - Prefer `.textContent` over `.innerText`. *(fixable)* - [prefer-includes](docs/rules/prefer-includes.md) - Prefer `.includes()` over `.indexOf()` and `Array#some()` when checking for existence or non-existence. *(partly fixable)* - [prefer-keyboard-event-key](docs/rules/prefer-keyboard-event-key.md) - Prefer `KeyboardEvent#key` over `KeyboardEvent#keyCode`. *(partly fixable)* - [prefer-math-trunc](docs/rules/prefer-math-trunc.md) - Enforce the use of `Math.trunc` instead of bitwise operators. *(partly fixable)* - [prefer-modern-dom-apis](docs/rules/prefer-modern-dom-apis.md) - Prefer `.before()` over `.insertBefore()`, `.replaceWith()` over `.replaceChild()`, prefer one of `.before()`, `.after()`, `.append()` or `.prepend()` over `insertAdjacentText()` and `insertAdjacentElement()`. *(fixable)* - [prefer-negative-index](docs/rules/prefer-negative-index.md) - Prefer negative index over `.length - index` for `{String,Array,TypedArray}#slice()` and `Array#splice()`. *(fixable)* - [prefer-number-properties](docs/rules/prefer-number-properties.md) - Prefer `Number` static properties over global ones. *(fixable)* - [prefer-optional-catch-binding](docs/rules/prefer-optional-catch-binding.md) - Prefer omitting the `catch` binding parameter. *(fixable)* - [prefer-query-selector](docs/rules/prefer-query-selector.md) - Prefer `.querySelector()` over `.getElementById()`, `.querySelectorAll()` over `.getElementsByClassName()` and `.getElementsByTagName()`. *(partly fixable)* - [prefer-reflect-apply](docs/rules/prefer-reflect-apply.md) - Prefer `Reflect.apply()` over `Function#apply()`. *(fixable)* - [prefer-regexp-test](docs/rules/prefer-regexp-test.md) - Prefer `RegExp#test()` over `String#match()` and `RegExp#exec()`. *(fixable)* - [prefer-set-has](docs/rules/prefer-set-has.md) - Prefer `Set#has()` over `Array#includes()` when checking for existence or non-existence. *(fixable)* - [prefer-spread](docs/rules/prefer-spread.md) - Prefer the spread operator over `Array.from()` and `Array#concat()`. *(partly fixable)* - [prefer-string-replace-all](docs/rules/prefer-string-replace-all.md) - Prefer `String#replaceAll()` over regex searches with the global flag. *(fixable)* - [prefer-string-slice](docs/rules/prefer-string-slice.md) - Prefer `String#slice()` over `String#substr()` and `String#substring()`. *(partly fixable)* - [prefer-string-starts-ends-with](docs/rules/prefer-string-starts-ends-with.md) - Prefer `String#startsWith()` & `String#endsWith()` over `RegExp#test()`. *(fixable)* - [prefer-string-trim-start-end](docs/rules/prefer-string-trim-start-end.md) - Prefer `String#trimStart()` / `String#trimEnd()` over `String#trimLeft()` / `String#trimRight()`. *(fixable)* - [prefer-ternary](docs/rules/prefer-ternary.md) - Prefer ternary expressions over simple `if-else` statements. *(fixable)* - [prefer-type-error](docs/rules/prefer-type-error.md) - Enforce throwing `TypeError` in type checking conditions. *(fixable)* - [prevent-abbreviations](docs/rules/prevent-abbreviations.md) - Prevent abbreviations. *(partly fixable)* - [string-content](docs/rules/string-content.md) - Enforce better string content. *(fixable)* - [throw-new-error](docs/rules/throw-new-error.md) - Require `new` when throwing an error. *(fixable)* ## Deprecated Rules See [docs/deprecated-rules.md](docs/deprecated-rules.md) ## Recommended config This plugin exports a [`recommended` config](index.js) that enforces good practices. Enable it in your `package.json` with the `extends` option: ```json { "name": "my-awesome-project", "eslintConfig": { "extends": "plugin:unicorn/recommended" } } ``` See the [ESLint docs](https://eslint.org/docs/user-guide/configuring#extending-configuration-files) for more information about extending config files. **Note**: This config will also enable the correct [parser options](https://eslint.org/docs/user-guide/configuring#specifying-parser-options) and [environment](https://eslint.org/docs/user-guide/configuring#specifying-environments). ## Maintainers - [Sindre Sorhus](https://github.com/sindresorhus) - [Adam Babcock](https://github.com/MrHen) - [futpib](https://github.com/futpib) - [Fisker Cheung](https://github.com/fisker) ###### Former - [Jeroen Engels](https://github.com/jfmengels) - [Sam Verschueren](https://github.com/SamVerschueren)