Package Exports

eslint-plugin-unicorn
eslint-plugin-unicorn/package.json

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (eslint-plugin-unicorn) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

eslint-plugin-unicorn

Various awesome ESLint rules

You might want to check out XO, which includes this plugin.

Propose or contribute a new rule ➡

Install

$ npm install --save-dev eslint eslint-plugin-unicorn

Usage

Configure it in package.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-document-cookie": "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-static-only-class": "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": "error",
            "unicorn/prefer-add-event-listener": "error",
            "unicorn/prefer-array-find": "error",
            "unicorn/prefer-array-flat": "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-module": "error",
            "unicorn/prefer-negative-index": "error",
            "unicorn/prefer-node-protocol": "error",
            "unicorn/prefer-number-properties": "error",
            "unicorn/prefer-object-has-own": "off",
            "unicorn/prefer-optional-catch-binding": "error",
            "unicorn/prefer-prototype-methods": "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-switch": "error",
            "unicorn/prefer-ternary": "error",
            "unicorn/prefer-type-error": "error",
            "unicorn/prevent-abbreviations": "error",
            "unicorn/require-array-join-separator": "error",
            "unicorn/require-number-to-fixed-digits-argument": "error",
            "unicorn/string-content": "off",
            "unicorn/throw-new-error": "error"
        }
    }
}

Rules

Each rule has emojis denoting:

✅ if it belongs to the recommended configuration
🔧 if some problems reported by the rule are automatically fixable by the --fix command line option
💡 if some problems reported by the rule are manually fixable by editor suggestions

Name	Description	✅	🔧	💡
better-regex	Improve regexes by making them shorter, consistent, and safer.	✅	🔧
catch-error-name	Enforce a specific parameter name in catch clauses.	✅	🔧
consistent-destructuring	Use destructured variables over properties.	✅	🔧	💡
consistent-function-scoping	Move function definitions to the highest possible scope.	✅
custom-error-definition	Enforce correct `Error` subclassing.		🔧
empty-brace-spaces	Enforce no spaces between braces.	✅	🔧
error-message	Enforce passing a `message` value when creating a built-in error.	✅
escape-case	Require escape sequences to use uppercase values.	✅	🔧
expiring-todo-comments	Add expiration conditions to TODO comments.	✅
explicit-length-check	Enforce explicitly comparing the `length` or `size` property of a value.	✅	🔧	💡
filename-case	Enforce a case style for filenames.	✅
import-index	Enforce importing index files with `.`.		🔧
import-style	Enforce specific import styles per module.	✅
new-for-builtins	Enforce the use of `new` for all builtins, except `String`, `Number`, `Boolean`, `Symbol` and `BigInt`.	✅	🔧
no-abusive-eslint-disable	Enforce specifying rules to disable in `eslint-disable` comments.	✅
no-array-callback-reference	Prevent passing a function reference directly to iterator methods.	✅		💡
no-array-for-each	Prefer `for…of` over `Array#forEach(…)`.	✅	🔧
no-array-push-push	Enforce combining multiple `Array#push()` into one call.	✅	🔧	💡
no-array-reduce	Disallow `Array#reduce()` and `Array#reduceRight()`.	✅
no-console-spaces	Do not use leading/trailing space between `console.log` parameters.	✅	🔧
no-document-cookie	Do not use `document.cookie` directly.	✅
no-for-loop	Do not use a `for` loop that can be replaced with a `for-of` loop.	✅	🔧
no-hex-escape	Enforce the use of Unicode escapes instead of hexadecimal escapes.	✅	🔧
no-instanceof-array	Require `Array.isArray()` instead of `instanceof Array`.	✅	🔧
no-keyword-prefix	Disallow identifiers starting with `new` or `class`.
no-lonely-if	Disallow `if` statements as the only statement in `if` blocks without `else`.	✅	🔧
no-nested-ternary	Disallow nested ternary expressions.	✅	🔧
no-new-array	Disallow `new Array()`.	✅	🔧	💡
no-new-buffer	Enforce the use of `Buffer.from()` and `Buffer.alloc()` instead of the deprecated `new Buffer()`.	✅	🔧	💡
no-null	Disallow the use of the `null` literal.	✅	🔧	💡
no-object-as-default-parameter	Disallow the use of objects as default parameters.	✅
no-process-exit	Disallow `process.exit()`.	✅
no-static-only-class	Forbid classes that only have static members.	✅	🔧
no-this-assignment	Disallow assigning `this` to a variable.	✅
no-unreadable-array-destructuring	Disallow unreadable array destructuring.	✅	🔧
no-unsafe-regex	Disallow unsafe regular expressions.
no-unused-properties	Disallow unused object properties.
no-useless-undefined	Disallow useless `undefined`.	✅	🔧
no-zero-fractions	Disallow number literals with zero fractions or dangling dots.	✅	🔧
number-literal-case	Enforce proper case for numeric literals.	✅	🔧
numeric-separators-style	Enforce the style of numeric separators by correctly grouping digits.	✅	🔧
prefer-add-event-listener	Prefer `.addEventListener()` and `.removeEventListener()` over `on`-functions.	✅	🔧
prefer-array-find	Prefer `.find(…)` over the first element from `.filter(…)`.	✅	🔧	💡
prefer-array-flat	Prefer `Array#flat()` over legacy techniques to flatten arrays.	✅	🔧
prefer-array-flat-map	Prefer `.flatMap(…)` over `.map(…).flat()`.	✅	🔧
prefer-array-index-of	Prefer `Array#indexOf()` over `Array#findIndex()` when looking for the index of an item.	✅	🔧	💡
prefer-array-some	Prefer `.some(…)` over `.find(…)`.	✅		💡
prefer-date-now	Prefer `Date.now()` to get the number of milliseconds since the Unix Epoch.	✅	🔧
prefer-default-parameters	Prefer default parameters over reassignment.	✅	🔧	💡
prefer-dom-node-append	Prefer `Node#append()` over `Node#appendChild()`.	✅	🔧
prefer-dom-node-dataset	Prefer using `.dataset` on DOM elements over `.setAttribute(…)`.	✅	🔧
prefer-dom-node-remove	Prefer `childNode.remove()` over `parentNode.removeChild(childNode)`.	✅	🔧	💡
prefer-dom-node-text-content	Prefer `.textContent` over `.innerText`.	✅	🔧
prefer-includes	Prefer `.includes()` over `.indexOf()` and `Array#some()` when checking for existence or non-existence.	✅	🔧	💡
prefer-keyboard-event-key	Prefer `KeyboardEvent#key` over `KeyboardEvent#keyCode`.	✅	🔧
prefer-math-trunc	Enforce the use of `Math.trunc` instead of bitwise operators.	✅	🔧	💡
prefer-modern-dom-apis	Prefer `.before()` over `.insertBefore()`, `.replaceWith()` over `.replaceChild()`, prefer one of `.before()`, `.after()`, `.append()` or `.prepend()` over `insertAdjacentText()` and `insertAdjacentElement()`.	✅	🔧
prefer-module	Prefer JavaScript modules (ESM) over CommonJS.	✅	🔧	💡
prefer-negative-index	Prefer negative index over `.length - index` for `{String,Array,TypedArray}#slice()`, `Array#splice()` and `Array#at()`.	✅	🔧
prefer-node-protocol	Prefer using the `node:` protocol when importing Node.js builtin modules.	✅	🔧
prefer-number-properties	Prefer `Number` static properties over global ones.	✅	🔧	💡
prefer-object-has-own	Prefer `Object.hasOwn(…)` over `Object.prototype.hasOwnProperty.call(…)`.		🔧
prefer-optional-catch-binding	Prefer omitting the `catch` binding parameter.	✅	🔧
prefer-prototype-methods	Prefer borrowing methods from the prototype instead of the instance.	✅	🔧
prefer-query-selector	Prefer `.querySelector()` over `.getElementById()`, `.querySelectorAll()` over `.getElementsByClassName()` and `.getElementsByTagName()`.	✅	🔧
prefer-reflect-apply	Prefer `Reflect.apply()` over `Function#apply()`.	✅	🔧
prefer-regexp-test	Prefer `RegExp#test()` over `String#match()` and `RegExp#exec()`.	✅	🔧
prefer-set-has	Prefer `Set#has()` over `Array#includes()` when checking for existence or non-existence.	✅	🔧	💡
prefer-spread	Prefer the spread operator over `Array.from(…)`, `Array#concat(…)` and `Array#slice()`.	✅	🔧	💡
prefer-string-replace-all	Prefer `String#replaceAll()` over regex searches with the global flag.		🔧
prefer-string-slice	Prefer `String#slice()` over `String#substr()` and `String#substring()`.	✅	🔧
prefer-string-starts-ends-with	Prefer `String#startsWith()` & `String#endsWith()` over `RegExp#test()`.	✅	🔧	💡
prefer-string-trim-start-end	Prefer `String#trimStart()` / `String#trimEnd()` over `String#trimLeft()` / `String#trimRight()`.	✅	🔧
prefer-switch	Prefer `switch` over multiple `else-if`.	✅	🔧
prefer-ternary	Prefer ternary expressions over simple `if-else` statements.	✅	🔧
prefer-type-error	Enforce throwing `TypeError` in type checking conditions.	✅	🔧
prevent-abbreviations	Prevent abbreviations.	✅	🔧
require-array-join-separator	Enforce using the separator argument with `Array#join()`.	✅	🔧
require-number-to-fixed-digits-argument	Enforce using the digits argument with `Number#toFixed()`.	✅	🔧
string-content	Enforce better string content.		🔧	💡
throw-new-error	Require `new` when throwing an error.	✅	🔧

Deprecated Rules

See docs/deprecated-rules.md

Recommended config

This plugin exports a recommended config that enforces good practices.

Enable it in your package.json with the extends option:

{
    "name": "my-awesome-project",
    "eslintConfig": {
        "extends": "plugin:unicorn/recommended"
    }
}

See the ESLint docs for more information about extending config files.

Note: This config will also enable the correct parser options and environment.

JSPM