eslint-plugin-clean-regex

An ESLint plugin for writing better regular expressions.

⚠️ Deprecated ⚠️

This project is deprecated.

Please use eslint-plugin-regexp instead.

What happened?

eslint-plugin-clean-regex and eslint-plugin-regexp have joined forces. We decided to work together on one ESLint plugin for JavaScript regexes. Since maintaining two plugins with similar rules takes too much work, I decided to stop working on eslint-plugin-clean-regex.

As of right now, eslint-plugin-regexp supports all rules of eslint-plugin-clean-regex along improvements to those rules and with many more useful rules.

Migration

See the migration guide.

About

This is an ESLint plugin to lint JavaScript regular expressions. Its goal is to help both beginners and experts to write better regular expressions by pointing out errors and suggesting improvements.

The plugin offers rules for possible errors, best practices, and coding style in regular expressions.

Right now, this project is still young (and many rules are opinionated). Feel free to open an issue if you think rules are too strict/lax/inflexible. Suggestions and feature requests are welcome as well!

Getting started

You'll need to install ESLint and eslint-plugin-clean-regex:

$ npm i eslint eslint-plugin-clean-regex --save-dev

Note: If you installed ESLint globally (using the -g flag) then you must also install eslint-plugin-clean-regex globally.

Add clean-regex to the plugins section of your .eslintrc configuration file (you can omit the eslint-plugin- prefix) and configure the rules you want:

{
    "plugins": [
        "clean-regex"
    ],
    "rules": {
        "clean-regex/rule-name": 2
    }
}

You can also use the recommended config:

{
    "plugins": [
        "clean-regex"
    ],
    "extends": [
        "plugin:clean-regex/recommended"
    ]
}

The setting of every rule in the recommended config can be found in the table below.

Highlights

Some highlights of the working and working-together of rules in the recommended config.

Optimize character classes

Before:

- /[0-9]/i
- /[^\s]/
- /[a-fA-F0-9]/i
- /[a-zA-Z0-9_-]/
- /[a-z\d\w]/
- /[\S\d]/
- /[\w\p{ASCII}]/u

After:

- /\d/
- /\S/
- /[a-f0-9]/i
- /[\w-]/
- /\w/
- /\S/
- /\p{ASCII}/u

Simplify patterns

Before:

- /(?:\w|\d)+/
- /(?:a|(b)|c|(?:d)|(?:ee)){0,}/
- /(?<!\w)a+(?=$)/mi
- /[\s\S]#[\0-\uFFFF]/ysi
- /\d*\w(?:[a-z_]|\d+)*/im

After:

- /\w+/
- /(?:[acd]|(b)|ee)*/
- /\ba+$/im
- /.#./sy
- /\w+/

Detect non-functional code and potential errors

- /\1(a)/        // `\1` won't work
- /a+b*?/        // `b*?` can be removed
- /(?:\b)?a/     // `(?:\b)?` can be removed
- /[a-z]+|Foo/i  // `Foo` can be removed
- /(?=a?)\w\Ba/  // `(?=a?)` and `\B` always accept and can be removed
- /[*/+-^&|]/    // `+-^` will match everything from \x2B to \x5E including all character A to Z

Supported Rules

Fixable rules are denoted with a 🔧.

Problems

Suggestions