eslint-plugin-unicorn

What is eslint-plugin-unicorn?

The eslint-plugin-unicorn package is a set of ESLint rules that aim to improve code quality by enforcing best practices, preventing common mistakes, and suggesting modern syntax and methods. It includes a variety of rules that are not covered by the core ESLint rules or other plugins, focusing on code enhancements and consistency.

What are eslint-plugin-unicorn's main functionalities?

Filename Case

Enforces a specific case for filenames, which can be configured to be kebab-case, camelCase, or snake_case. This helps maintain consistency in the naming of files across a project.

"unicorn/filename-case": ["error", {"case": "kebabCase"}]

Number Literal Case

Enforces lowercase identifier and uppercase value for number literals, improving readability and consistency in the code.

"unicorn/number-literal-case": "error"

Prevent Abbreviations

Discourages the use of abbreviations in variable names, function names, and other identifiers to improve code clarity and readability.

"unicorn/prevent-abbreviations": ["error", {"replacements": {"temp": false, "err": {"error": true}}}]

Better Regex

Suggests simpler and more optimized regular expressions to improve performance and readability.

"unicorn/better-regex": "error"

Consistent Function Scoping

Enforces that functions are defined at the highest possible level, which can help with readability and reduce the complexity of nested functions.

"unicorn/consistent-function-scoping": "error"

Other packages similar to eslint-plugin-unicorn

eslint-plugin-import

This plugin provides linting rules related to ES2015+ import/export syntax, helping to ensure proper import order, naming, and file path correctness. It is similar to eslint-plugin-unicorn in that it enforces best practices, but it focuses specifically on module import and export issues.

eslint-plugin-promise

This plugin enforces best practices for JavaScript promises. It is similar to eslint-plugin-unicorn in its goal to improve code quality, but it focuses specifically on the use of promises and asynchronous code.

eslint-plugin-jsx-a11y

This plugin checks JSX code for accessibility issues, ensuring that web applications are accessible to users with disabilities. While eslint-plugin-unicorn focuses on general JavaScript code quality, eslint-plugin-jsx-a11y focuses on accessibility concerns in React and JSX.

eslint-plugin-react

This plugin provides React-specific linting rules. It is similar to eslint-plugin-unicorn in that it helps maintain code quality and consistency, but it is tailored specifically for React development.

README

eslint-plugin-unicorn

Various awesome ESLint rules

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

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": 2017,
			"sourceType": "module"
		},
		"plugins": [
			"unicorn"
		],
		"rules": {
			"unicorn/catch-error-name": ["error", {"name": "err"}],
			"unicorn/explicit-length-check": "error",
			"unicorn/filename-case": ["error", {"case": "kebabCase"}],
			"unicorn/no-abusive-eslint-disable": "error",
			"unicorn/no-process-exit": "error",
			"unicorn/throw-new-error": "error",
			"unicorn/number-literal-case": "error",
			"unicorn/escape-case": "error",
			"unicorn/no-array-instanceof": "error",
			"unicorn/no-new-buffer": "error",
			"unicorn/no-hex-escape": "error",
			"unicorn/custom-error-definition": "off",
			"unicorn/prefer-starts-ends-with": "error",
			"unicorn/prefer-type-error": "error",
			"unicorn/no-fn-reference-in-iterator": "off",
			"unicorn/import-index": "error",
			"unicorn/new-for-builtins": "error",
			"unicorn/regex-shorthand": "error",
			"unicorn/prefer-spread": "error",
			"unicorn/error-message": "error",
			"unicorn/no-unsafe-regex": "off",
			"unicorn/prefer-add-event-listener": "error"
		}
	}
}

Rules

• catch-error-name - Enforce a specific parameter name in catch clauses.
• explicit-length-check - Enforce explicitly comparing the length property of a value. (partly fixable)
• filename-case - Enforce a case style for filenames.
• no-abusive-eslint-disable - Enforce specifying rules to disable in eslint-disable comments.
• no-process-exit - Disallow process.exit().
• throw-new-error - Require new when throwing an error. (fixable)
• number-literal-case - Enforce lowercase identifier and uppercase value for number literals. (fixable)
• escape-case - Require escape sequences to use uppercase values. (fixable)
• no-array-instanceof - Require Array.isArray() instead of instanceof Array. (fixable)
• no-new-buffer - Enforce the use of Buffer.from() and Buffer.alloc() instead of the deprecated new Buffer(). (fixable)
• no-hex-escape - Enforce the use of unicode escapes instead of hexadecimal escapes. (fixable)
• custom-error-definition - Enforce correct Error subclassing. (fixable)
• prefer-starts-ends-with - Prefer String#startsWith & String#endsWith over more complex alternatives.
• prefer-type-error - Enforce throwing TypeError in type checking conditions. (fixable)
• no-fn-reference-in-iterator - Prevents passing a function reference directly to iterator methods. (fixable)
• import-index - Enforce importing index files with .. (fixable)
• new-for-builtins - Enforce the use of new for all builtins, except String, Number and Boolean. (fixable)
• regex-shorthand - Enforce the use of regex shorthands to improve readability. (fixable)
• prefer-spread - Prefer the spread operator over Array.from(). (fixable)
• error-message - Enforce passing a message value when throwing a built-in error.
• no-unsafe-regex - Disallow unsafe regular expressions.
• prefer-add-event-listener - Prefer addEventListener over on-functions. (fixable)

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": {
		"plugins": [
			"unicorn"
		],
		"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.

Maintainers

• Sindre Sorhus
• James Talmage
• Jeroen Engels
• Sam Verschueren
• John Wu

License

MIT