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Awesome Open Source

eslint-plugin-unicorn Coverage Status npm version

More than 100 powerful ESLint rules

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

**Propose or contribute a new rule **


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


Use a preset config or configure each rules in package.json.

	"name": "my-awesome-project",
	"eslintConfig": {
		"env": {
			"es2022": true
		"parserOptions": {
			"ecmaVersion": "latest",
			"sourceType": "module"
		"plugins": [
		"rules": {
			"unicorn/better-regex": "error",
			"unicorn/": "error"


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-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 forof over the forEach method.
no-array-method-this-argument Disallow using the this argument in array methods.
no-array-push-push Enforce combining multiple Array#push() into one call.
no-array-reduce Disallow Array#reduce() and Array#reduceRight().
no-await-expression-member Disallow member access from await expression.
no-console-spaces Do not use leading/trailing space between console.log parameters.
no-document-cookie Do not use document.cookie directly.
no-empty-file Disallow empty files.
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-invalid-remove-event-listener Prevent calling EventTarget#removeEventListener() with the result of an expression.
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 Disallow classes that only have static members.
no-thenable Disallow then property.
no-this-assignment Disallow assigning this to a variable.
no-unreadable-array-destructuring Disallow unreadable array destructuring.
no-unreadable-iife Disallow unreadable IIFEs.
no-unsafe-regex Disallow unsafe regular expressions.
no-unused-properties Disallow unused object properties.
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 Promise.resolve/reject() in async functions or promise callbacks
no-useless-spread Disallow unnecessary spread.
no-useless-switch-case Disallow useless case in switch statements.
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 .filter().length check and .find().
prefer-at Prefer .at() method for index access and String#charAt().
prefer-code-point Prefer String#codePointAt() over String#charCodeAt() and String.fromCodePoint() over String.fromCharCode().
prefer-date-now Prefer 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 calling attribute methods.
prefer-dom-node-remove Prefer childNode.remove() over parentNode.removeChild(childNode).
prefer-dom-node-text-content Prefer .textContent over .innerText.
prefer-event-target Prefer EventTarget over EventEmitter.
prefer-export-from Prefer exportfrom when re-exporting.
prefer-includes Prefer .includes() over .indexOf() and Array#some() when checking for existence or non-existence.
prefer-json-parse-buffer Prefer reading a JSON file as a buffer.
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-modern-math-apis Prefer modern Math APIs over legacy patterns.
prefer-module Prefer JavaScript modules (ESM) over CommonJS.
prefer-native-coercion-functions Prefer using String, Number, BigInt, Boolean, and Symbol directly.
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-from-entries Prefer using Object.fromEntries() to transform a list of key-value pairs into an object.
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(), Array#slice() and String#split('').
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-top-level-await Prefer top-level await over top-level promises and async function calls.
prefer-type-error Enforce throwing TypeError in type checking conditions.
prevent-abbreviations Prevent abbreviations.
relative-url-style Enforce consistent relative URL style.
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().
require-post-message-target-origin Enforce using the targetOrigin argument with window.postMessage().
string-content Enforce better string content.
template-indent Fix whitespace-insensitive template indentation.
text-encoding-identifier-case Enforce consistent case for text encoding identifiers.
throw-new-error Require new when throwing an error.

Deprecated Rules

See docs/

Preset configs

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

Note: Preset configs will also enable the correct parser options and environment.

Recommended config

This plugin exports a recommended config that enforces good practices.

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

All config

This plugin exports an all config that makes use of all rules (except for deprecated ones).

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



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