More than 100 powerful ESLint rules
npm install eslint-plugin-unicorn-x> More than 100 powerful ESLint rules
A modern, faster and lighter fork of eslint-plugin-unicorn.
``sh`
npm install --save-dev eslint eslint-plugin-unicorn-x
Requires ESLint >=9.29.0 and flat config.
Use a preset config or configure each rule in eslint.config.js.
If you don't use the preset, ensure you use the same languageOptions config as below.
`js
import eslintPluginUnicorn from 'eslint-plugin-unicorn-x';
import globals from 'globals';
export default [
{
languageOptions: {
globals: globals.builtin,
},
plugins: {
unicorn: eslintPluginUnicorn,
},
rules: {
'unicorn-x/better-regex': 'error',
'unicorn-x/…': 'error',
},
},
// …
];
`
This fork exists to provide various performance improvements and a reduced install footprint.
Much of this cannot be contributed upstream due to differences in opinion on dependency selection, backwards compatibility requirements, and so on.
We will contribute what we can upstream, and continue to track the original, allowing this plugin to exist as a mostly drop-in replacement to get an easy bump in lint performance.
If you are migrating from eslint-plugin-unicorn, simply replace unicorn with unicorn-x in your rules and update the plugin import path:
`json5
{
"rules": {
// before
"unicorn/better-regex": "error",
// after
"unicorn-x/better-regex": "error",
}
}
`
💼 Configurations enabled in.\
✅ Set in the recommended configuration.\--fix
🔧 Automatically fixable by the CLI option.\
💡 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-assert | Enforce consistent assertion style with node:assert. | ✅ | 🔧 | |Date
| consistent-date-clone | Prefer passing directly to the constructor when cloning. | ✅ | 🔧 | |indexOf()
| consistent-destructuring | Use destructured variables over properties. | | | 💡 |
| consistent-empty-array-spread | Prefer consistent types when spreading a ternary in an array literal. | ✅ | 🔧 | |
| consistent-existence-index-check | Enforce consistent style for element existence checks with , lastIndexOf(), findIndex(), and findLastIndex(). | ✅ | 🔧 | |Error
| consistent-function-scoping | Move function definitions to the highest possible scope. | ✅ | | |
| custom-error-definition | Enforce correct subclassing. | | 🔧 | |message
| empty-brace-spaces | Enforce no spaces between braces. | ✅ | 🔧 | |
| error-message | Enforce passing a value when creating a built-in error. | ✅ | | |length
| escape-case | Require escape sequences to use uppercase or lowercase values. | ✅ | 🔧 | |
| expiring-todo-comments | Add expiration conditions to TODO comments. | ✅ | | |
| explicit-length-check | Enforce explicitly comparing the or size property of a value. | ✅ | 🔧 | 💡 |new
| filename-case | Enforce a case style for filenames. | ✅ | | |
| import-style | Enforce specific import styles per module. | ✅ | | |
| new-for-builtins | Enforce the use of for all builtins, except String, Number, Boolean, Symbol and BigInt. | ✅ | 🔧 | 💡 |eslint-disable
| no-abusive-eslint-disable | Enforce specifying rules to disable in comments. | ✅ | | |this
| no-accessor-recursion | Disallow recursive access to within getters and setters. | ✅ | | |for…of
| no-anonymous-default-export | Disallow anonymous functions and classes as the default export. | ✅ | | 💡 |
| no-array-callback-reference | Prevent passing a function reference directly to iterator methods. | ✅ | | 💡 |
| no-array-for-each | Prefer over the forEach method. | ✅ | 🔧 | 💡 |this
| no-array-method-this-argument | Disallow using the argument in array methods. | ✅ | 🔧 | 💡 |Array#reduce()
| no-array-reduce | Disallow and Array#reduceRight(). | ✅ | | |Array#toReversed()
| no-array-reverse | Prefer over Array#reverse(). | ✅ | | 💡 |await
| no-await-expression-member | Disallow member access from await expression. | ✅ | 🔧 | |
| no-await-in-promise-methods | Disallow using in Promise method parameters. | ✅ | | 💡 |console.log
| no-console-spaces | Do not use leading/trailing space between parameters. | ✅ | 🔧 | |document.cookie
| no-document-cookie | Do not use directly. | ✅ | | |for
| no-empty-file | Disallow empty files. | ✅ | | |
| no-for-loop | Do not use a loop that can be replaced with a for-of loop. | ✅ | 🔧 | 💡 |instanceof
| no-hex-escape | Enforce the use of Unicode escapes instead of hexadecimal escapes. | ✅ | 🔧 | |
| no-instanceof-builtins | Disallow with built-in objects | ✅ | 🔧 | 💡 |fetch()
| no-invalid-fetch-options | Disallow invalid options in and new Request(). | ✅ | | |EventTarget#removeEventListener()
| no-invalid-remove-event-listener | Prevent calling with the result of an expression. | ✅ | | |new
| no-keyword-prefix | Disallow identifiers starting with or class. | | | |if
| no-lonely-if | Disallow statements as the only statement in if blocks without else. | ✅ | 🔧 | |depth
| no-magic-array-flat-depth | Disallow a magic number as the argument in Array#flat(…). | ✅ | | |new Array()
| no-named-default | Disallow named usage of default import and export. | ✅ | 🔧 | |
| no-negated-condition | Disallow negated conditions. | ✅ | 🔧 | |
| no-negation-in-equality-check | Disallow negated expression in equality check. | ✅ | | 💡 |
| no-nested-ternary | Disallow nested ternary expressions. | ✅ | 🔧 | |
| no-new-array | Disallow . | ✅ | 🔧 | 💡 |Buffer.from()
| no-new-buffer | Enforce the use of and Buffer.alloc() instead of the deprecated new Buffer(). | ✅ | 🔧 | 💡 |null
| no-null | Disallow the use of the literal. | ✅ | 🔧 | 💡 |process.exit()
| no-object-as-default-parameter | Disallow the use of objects as default parameters. | ✅ | | |
| no-process-exit | Disallow . | ✅ | | |Promise
| no-single-promise-in-promise-methods | Disallow passing single-element arrays to methods. | ✅ | 🔧 | 💡 |then
| no-static-only-class | Disallow classes that only have static members. | ✅ | 🔧 | |
| no-thenable | Disallow property. | ✅ | | |this
| no-this-assignment | Disallow assigning to a variable. | ✅ | | |undefined
| no-typeof-undefined | Disallow comparing using typeof. | ✅ | 🔧 | 💡 |1
| no-unnecessary-array-flat-depth | Disallow using as the depth argument of Array#flat(). | ✅ | 🔧 | |.length
| no-unnecessary-array-splice-count | Disallow using or Infinity as the deleteCount or skipCount argument of Array#{splice,toSpliced}(). | ✅ | 🔧 | |.length
| no-unnecessary-await | Disallow awaiting non-promise values. | ✅ | 🔧 | |
| no-unnecessary-polyfills | Enforce the use of built-in methods instead of unnecessary polyfills. | ✅ | | |
| no-unnecessary-slice-end | Disallow using or Infinity as the end argument of {Array,String,TypedArray}#slice(). | ✅ | 🔧 | |Error.captureStackTrace(…)
| no-unreadable-array-destructuring | Disallow unreadable array destructuring. | ✅ | 🔧 | |
| no-unreadable-iife | Disallow unreadable IIFEs. | ✅ | | |
| no-unused-properties | Disallow unused object properties. | | | |
| no-useless-error-capture-stack-trace | Disallow unnecessary . | ✅ | 🔧 | |Promise.resolve/reject()
| no-useless-fallback-in-spread | Disallow useless fallback when spreading in object literals. | ✅ | 🔧 | |
| no-useless-length-check | Disallow useless array length check. | ✅ | 🔧 | |
| no-useless-promise-resolve-reject | Disallow returning/yielding in async functions or promise callbacks | ✅ | 🔧 | |undefined
| no-useless-spread | Disallow unnecessary spread. | ✅ | 🔧 | |
| no-useless-switch-case | Disallow useless case in switch statements. | ✅ | | 💡 |
| no-useless-undefined | Disallow useless . | ✅ | 🔧 | |.addEventListener()
| 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 and .removeEventListener() over on-functions. | ✅ | 🔧 | |.find(…)
| prefer-array-find | Prefer and .findLast(…) over the first or last element from .filter(…). | ✅ | 🔧 | 💡 |Array#flat()
| prefer-array-flat | Prefer over legacy techniques to flatten arrays. | ✅ | 🔧 | |.flatMap(…)
| prefer-array-flat-map | Prefer over .map(…).flat(). | ✅ | 🔧 | |Array#{indexOf,lastIndexOf}()
| prefer-array-index-of | Prefer over Array#{findIndex,findLastIndex}() when looking for the index of an item. | ✅ | 🔧 | 💡 |.some(…)
| prefer-array-some | Prefer over .filter(…).length check and .{find,findLast,findIndex,findLastIndex}(…). | ✅ | 🔧 | 💡 |.at()
| prefer-at | Prefer method for index access and String#charAt(). | ✅ | 🔧 | 💡 |Blob#arrayBuffer()
| prefer-blob-reading-methods | Prefer over FileReader#readAsArrayBuffer(…) and Blob#text() over FileReader#readAsText(…). | ✅ | | |this
| prefer-class-fields | Prefer class field declarations over assignments in constructors. | ✅ | 🔧 | 💡 |String#codePointAt(…)
| prefer-code-point | Prefer over String#charCodeAt(…) and String.fromCodePoint(…) over String.fromCharCode(…). | ✅ | | 💡 |Date.now()
| prefer-date-now | Prefer to get the number of milliseconds since the Unix Epoch. | ✅ | 🔧 | |Node#append()
| prefer-default-parameters | Prefer default parameters over reassignment. | ✅ | | 💡 |
| prefer-dom-node-append | Prefer over Node#appendChild(). | ✅ | 🔧 | |.dataset
| prefer-dom-node-dataset | Prefer using on DOM elements over calling attribute methods. | ✅ | 🔧 | |childNode.remove()
| prefer-dom-node-remove | Prefer over parentNode.removeChild(childNode). | ✅ | 🔧 | 💡 |.textContent
| prefer-dom-node-text-content | Prefer over .innerText. | ✅ | | 💡 |EventTarget
| prefer-event-target | Prefer over EventEmitter. | ✅ | | |export…from
| prefer-export-from | Prefer when re-exporting. | ✅ | 🔧 | 💡 |globalThis
| prefer-global-this | Prefer over window, self, and global. | ✅ | 🔧 | |import.meta.{dirname,filename}
| prefer-import-meta-properties | Prefer over legacy techniques for getting file paths. | | 🔧 | |.includes()
| prefer-includes | Prefer over .indexOf(), .lastIndexOf(), and Array#some() when checking for existence or non-existence. | ✅ | 🔧 | 💡 |KeyboardEvent#key
| prefer-json-parse-buffer | Prefer reading a JSON file as a buffer. | | 🔧 | |
| prefer-keyboard-event-key | Prefer over KeyboardEvent#keyCode. | ✅ | 🔧 | |Math.min()
| prefer-logical-operator-over-ternary | Prefer using a logical operator over a ternary. | ✅ | | 💡 |
| prefer-math-min-max | Prefer and Math.max() over ternaries for simple comparisons. | ✅ | 🔧 | |Math.trunc
| prefer-math-trunc | Enforce the use of instead of bitwise operators. | ✅ | 🔧 | 💡 |.before()
| prefer-modern-dom-apis | Prefer over .insertBefore(), .replaceWith() over .replaceChild(), prefer one of .before(), .after(), .append() or .prepend() over insertAdjacentText() and insertAdjacentElement(). | ✅ | 🔧 | |Math
| prefer-modern-math-apis | Prefer modern APIs over legacy patterns. | ✅ | 🔧 | |String
| prefer-module | Prefer JavaScript modules (ESM) over CommonJS. | ✅ | 🔧 | 💡 |
| prefer-native-coercion-functions | Prefer using , Number, BigInt, Boolean, and Symbol directly. | ✅ | 🔧 | |.length - index
| prefer-negative-index | Prefer negative index over when possible. | ✅ | 🔧 | |node:
| prefer-node-protocol | Prefer using the protocol when importing Node.js builtin modules. | ✅ | 🔧 | |Number
| prefer-number-properties | Prefer static properties over global ones. | ✅ | 🔧 | 💡 |Object.fromEntries(…)
| prefer-object-from-entries | Prefer using to transform a list of key-value pairs into an object. | ✅ | 🔧 | |catch
| prefer-optional-catch-binding | Prefer omitting the binding parameter. | ✅ | 🔧 | |.querySelector()
| prefer-prototype-methods | Prefer borrowing methods from the prototype instead of the instance. | ✅ | 🔧 | |
| prefer-query-selector | Prefer over .getElementById(), .querySelectorAll() over .getElementsByClassName() and .getElementsByTagName() and .getElementsByName(). | ✅ | 🔧 | |Reflect.apply()
| prefer-reflect-apply | Prefer over Function#apply(). | ✅ | 🔧 | |RegExp#test()
| prefer-regexp-test | Prefer over String#match() and RegExp#exec(). | ✅ | 🔧 | 💡 |Set#has()
| prefer-set-has | Prefer over Array#includes() when checking for existence or non-existence. | ✅ | 🔧 | 💡 |Set#size
| prefer-set-size | Prefer using instead of Array#length. | ✅ | 🔧 | |Array#push()
| prefer-single-call | Enforce combining multiple , Element#classList.{add,remove}(), and importScripts() into one call. | ✅ | 🔧 | 💡 |Array.from(…)
| prefer-spread | Prefer the spread operator over , Array#concat(…), Array#{slice,toSpliced}() and String#split(''). | ✅ | 🔧 | 💡 |String.raw
| prefer-string-raw | Prefer using the tag to avoid escaping \. | ✅ | 🔧 | |String#replaceAll()
| prefer-string-replace-all | Prefer over regex searches with the global flag. | ✅ | 🔧 | |String#slice()
| prefer-string-slice | Prefer over String#substr() and String#substring(). | ✅ | 🔧 | |String#startsWith()
| prefer-string-starts-ends-with | Prefer & String#endsWith() over RegExp#test(). | ✅ | 🔧 | 💡 |String#trimStart()
| prefer-string-trim-start-end | Prefer / String#trimEnd() over String#trimLeft() / String#trimRight(). | ✅ | 🔧 | |structuredClone
| prefer-structured-clone | Prefer using to create a deep clone. | ✅ | | 💡 |switch
| prefer-switch | Prefer over multiple else-if. | ✅ | 🔧 | |if-else
| prefer-ternary | Prefer ternary expressions over simple statements. | ✅ | 🔧 | |TypeError
| prefer-top-level-await | Prefer top-level await over top-level promises and async function calls. | ✅ | | 💡 |
| prefer-type-error | Enforce throwing in type checking conditions. | ✅ | 🔧 | |Array#join()
| prevent-abbreviations | Prevent abbreviations. | ✅ | 🔧 | |
| relative-url-style | Enforce consistent relative URL style. | ✅ | 🔧 | 💡 |
| require-array-join-separator | Enforce using the separator argument with . | ✅ | 🔧 | |Number#toFixed()
| require-module-specifiers | Require non-empty specifier list in import and export statements. | ✅ | 🔧 | 💡 |
| require-number-to-fixed-digits-argument | Enforce using the digits argument with . | ✅ | 🔧 | |targetOrigin
| require-post-message-target-origin | Enforce using the argument with window.postMessage(). | | | 💡 |case
| string-content | Enforce better string content. | | 🔧 | 💡 |
| switch-case-braces | Enforce consistent brace style for clauses. | ✅ | 🔧 | |new
| template-indent | Fix whitespace-insensitive template indentation. | ✅ | 🔧 | |
| text-encoding-identifier-case | Enforce consistent case for text encoding identifiers. | ✅ | 🔧 | 💡 |
| throw-new-error | Require when creating an error. | ✅ | 🔧 | |
See the list.
See the ESLint docs for more information about extending config files.
Note: Preset configs will also enable the correct language options.
This plugin exports a recommended config that enforces good practices.
`js
import eslintPluginUnicorn from 'eslint-plugin-unicorn-x';
export default [
// …
eslintPluginUnicorn.configs.recommended,
{
rules: {
'unicorn-x/better-regex': 'warn',
},
},
];
`
This plugin exports an all that makes use of all rules (except for deprecated ones).
`js
import eslintPluginUnicorn from 'eslint-plugin-unicorn-x';
export default [
// …
eslintPluginUnicorn.configs.all,
{
rules: {
'unicorn-x/better-regex': 'warn',
},
},
];
``