eslint-doc-generator

Automatic documentation generator for ESLint plugins and rules. Inspired by documentation conventions from ESLint and top ESLint plugins.

Generates the following documentation covering a wide variety of rule metadata:

• README.md rules table
• README.md configs table
• Rule doc titles and notices
• Rule doc options lists

Also performs configurable section consistency checks on rule docs:

• Contains an ## Options or ## Config section and mentions each named option (for rules with options)

Table of contents

• Motivation
• Setup
  • Scripts
  • Update README.md
  • Update rule docs
  • Configure linting
• Usage
• Examples
  • Rules list table
  • Configs list table
  • Rule doc notices
  • Rule doc options lists
  • Users
• Configuration options
  • Column and notice types
  • --config-format
  • --rule-doc-title-format
  • Configuration file
  • Badges
• Compatibility
  • Build tools
  • markdownlint
  • prettier
• Semantic versioning policy
• Related

Motivation

• Standardize documentation across thousands of ESLint plugins and rules
• Improve the discoverability of key rule information and thus rule usability
• Streamline the process of adding/updating rules while ensuring documentation is kept up-to-date
• Eliminate the custom documentation scripts and tests previously built and maintained by many ESLint plugins

Setup

Install it:

npm i --save-dev eslint-doc-generator

Scripts

Add scripts to package.json:

• Both a lint script to ensure everything is up-to-date in CI and an update script for contributors to run locally
• Add any config options in the update:eslint-docs script only (or use a config file)
• Alternative scripts may be needed with build tools, markdownlint, or prettier

{
  "scripts": {
    "lint": "npm-run-all \"lint:*\"",
    "lint:docs": "markdownlint \"**/*.md\"",
    "lint:eslint-docs": "npm run update:eslint-docs -- --check",
    "lint:js": "eslint .",
    "update:eslint-docs": "eslint-doc-generator"
  }
}

Update README.md

Delete any old rules list from your README.md. A new one will be automatically added to your ## Rules section (along with the following marker comments if they don't already exist):

<!-- begin auto-generated rules list -->
<!-- end auto-generated rules list -->

Optionally, add these marker comments to your README.md in a ## Configs section or similar location (uses the meta.docs.description property exported by each config if available):

<!-- begin auto-generated configs list -->
<!-- end auto-generated configs list -->

Update rule docs

Delete any old recommended/fixable/etc. notices from your rule docs. A new title and notices will be automatically added to the top of each rule doc (along with a marker comment if it doesn't already exist).

<!-- end auto-generated rule header -->

Optionally, add these marker comments to your rule docs in an ## Options section or similar location:

<!-- begin auto-generated rule options list -->
<!-- end auto-generated rule options list -->

Note that rule option lists are subject-to-change as we add support for more kinds and properties of schemas. To fully take advantage of them, you'll want to ensure your rules have the meta.schema property fleshed out with properties like description, type, enum, default, required, deprecated.

Configure linting

And be sure to enable the recommended rules from eslint-plugin-eslint-plugin as well as:

• eslint-plugin/require-meta-docs-description to ensure your rules have consistent descriptions for use in the generated docs
• eslint-plugin/require-meta-docs-url to ensure your rule docs are linked to by editors on highlighted violations
• eslint-plugin/require-meta-schema to ensure your rules have schemas for use in determining options

Usage

Run the script from package.json to start out or any time you add a rule or update rule metadata in your plugin:

npm run update:eslint-docs

Examples

For examples, see our users or the in-house examples below. Note that the in-house examples intentionally show all possible columns and notices.

Rules list table

See the generated rules table and legend in our example README.md.

Configs list table

See the generated configs table in our example README.md.

Rule doc notices

See the generated rule doc title and notices in our example rule docs no-foo.md, prefer-bar.md, require-baz.md.

Rule doc options lists

See the generated rule doc options lists in our example rule doc no-foo.md.

Users

This tool is used by popular ESLint plugins like:

• eslint-plugin-ava
• eslint-plugin-ember
• eslint-plugin-eslint-plugin
• eslint-plugin-import
• eslint-plugin-jest
• eslint-plugin-jsx-a11y
• eslint-plugin-promise
• eslint-plugin-qunit
• eslint-plugin-react
• eslint-plugin-unicorn

Configuration options

These can be provided as CLI options or as config file options. All options are optional.

The CLI has an optional path argument if you need to point the CLI to an ESLint plugin directory that isn't just the current directory:

eslint-doc-generator path/to/eslint-plugin

There's also a postprocess option that's only available via a config file.

| Name | Description | Default | | :-- | :-- | :-- | | --check | Whether to check for and fail if there is a diff. Any diff will be displayed but no output will be written to files. Typically used during CI. | false | | --config-emoji | Custom emoji to use for a config. Format is config-name,emoji. Option can be repeated. | Default emojis are provided for common configs. See Badges for an alternative to emojis. | | --config-format | The format to use for config names. See choices in below table. | name | | --ignore-config | Config to ignore from being displayed. Often used for an all config. Option can be repeated. | | | --ignore-deprecated-rules | Whether to ignore deprecated rules from being checked, displayed, or updated. | false | | --init-rule-docs | Whether to create rule doc files if they don't yet exist. | false | | --path-rule-doc | Path to markdown file for each rule doc. Use {name} placeholder for the rule name. A function can also be provided for this option via a config file. | docs/rules/{name}.md | | --path-rule-list | Path to markdown file where the rules table list should live. Option can be repeated. | README.md | | --rule-doc-notices | Ordered, comma-separated list of notices to display in rule doc. Non-applicable notices will be hidden. See choices in below table. | deprecated, configs, fixableAndHasSuggestions, requiresTypeChecking | | --rule-doc-section-exclude | Disallowed section in each rule doc. Exit with failure if present. Option can be repeated. | | --rule-doc-section-include | Required section in each rule doc. Exit with failure if missing. Option can be repeated. | | --rule-doc-section-options | Whether to require an "Options" or "Config" rule doc section and mention of any named options for rules with options. | true | | --rule-doc-title-format | The format to use for rule doc titles. See choices in below table. | desc-parens-prefix-name | | --rule-list-columns | Ordered, comma-separated list of columns to display in rule list. Empty columns will be hidden. See choices in below table. | name, description, configsError, configsWarn, configsOff, fixable, hasSuggestions, requiresTypeChecking, deprecated | | --rule-list-split | Rule property(s) to split the rules list by. A separate list and header will be created for each value. Example: meta.type. A function can also be provided for this option via a config file. | | | --url-configs | Link to documentation about the ESLint configurations exported by the plugin. | | | --url-rule-doc | Link to documentation for each rule. Useful when it differs from the rule doc path on disk (e.g. custom documentation site in use). Use {name} placeholder for the rule name. A function can also be provided for this option via a config file. | |

Column and notice types

These are the types of rule metadata that are available for display in rule list columns (--rule-list-columns) and/or rule doc notices (--rule-doc-notices).

| Emoji | Type | Column? | Notice? | Description | | :-- | :-- | :-- | :-- | :-- | | 💼 | configsError | Yes | No | Whether a rule is set to error in a config. | | 🚫 | configsOff | Yes | No | Whether a rule is set to off in a config. | | ⚠️ | configsWarn | Yes | No | Whether a rule is set to warn in a config. | | 💼 | configs | No | Yes | What configs set a rule to what severities. | | ❌ | deprecated | Yes | Yes | Whether a rule is deprecated (i.e. likely to be removed/renamed in a future major version). | | | description | Yes | Yes | The rule description. | | 🔧💡 | fixableAndHasSuggestions | Yes | Yes | Whether a rule is fixable and/or has suggestions. | | 🔧 | fixable | Yes | Yes | Whether a rule is fixable. | | 💡 | hasSuggestions | Yes | Yes | Whether a rule has suggestions. | | | name | Yes | No | The rule name. | | ⚙️ | options | Yes | Yes | Whether a rule has options. | | 💭 | requiresTypeChecking | Yes | Yes | Whether a rule requires type checking. | | 🗂️ | type | Yes | Yes | The rule type (problem, suggestion, or layout). |

--config-format

Where recommended is the config name and eslint-plugin-test is the plugin name.

| Value | Example | | :-- | :-- | | name (default) | recommended | | plugin-colon-prefix-name | plugin:test/recommended | | prefix-name | test/recommended |

--rule-doc-title-format

Where no-foo is the rule name, Disallow use of foo is the rule description, and eslint-plugin-test is the plugin name.

| Value | Example | | :-- | :-- | | desc | # Disallow use of foo | | desc-parens-name | # Disallow use of foo (no-foo) | | desc-parens-prefix-name (default) | # Disallow use of foo (test/no-foo) | | name | # no-foo | prefix-name | # test/no-foo |

Configuration file

There are a few ways to create a config file (as an alternative to passing the options via CLI):

• An object exported by .eslint-doc-generatorrc.js, .eslint-doc-generatorrc.json, or any other config file format/name supported by cosmiconfig
• An object under the eslint-doc-generator key in package.json

Config files support all the CLI options but in camelCase.

Some options are exclusive to a JavaScript-based config file:

• postprocess - A function-only option useful for applying custom transformations such as formatting with tools like prettier. See prettier example.
• ruleListSplit with a function - This is useful for customizing the grouping of rules into lists.

Example .eslint-doc-generatorrc.js:

/** @type {import('eslint-doc-generator').GenerateOptions} */
const config = {
  ignoreConfig: ['all'],
};

module.exports = config;

Example .eslint-doc-generatorrc.js with pathRuleDoc function:

/** @type {import('eslint-doc-generator').GenerateOptions} */
const config = {
  pathRuleDoc(name) {
    // e.g. rule name format is `some-plugin/some-rule`, and rule is in a monorepo under different package.
    const [plugin, rule] = name.split("/");
    return `packages/eslint-plugin-${plugin}/src/rules/${rule}.md`;
  },
};

module.exports = config;

Example .eslint-doc-generatorrc.js with ruleListSplit function:

/** @type {import('eslint-doc-generator').GenerateOptions} */
const config = {
  ruleListSplit(rules) {
    return [
      {
        // No header for this list.
        rules: rules.filter(([name, rule]) => !rule.meta.someProp),
      },
      {
        title: 'Foo',
        rules: rules.filter(([name, rule]) => rule.meta.someProp === 'foo'),
      },
      {
        title: 'Bar',
        rules: rules.filter(([name, rule]) => rule.meta.someProp === 'bar'),
      },
    ];
  },
};

module.exports = config;

Example .eslint-doc-generatorrc.js with urlRuleDoc function:

/** @type {import('eslint-doc-generator').GenerateOptions} */
const config = {
  urlRuleDoc(name, page) {
    if (page === 'README.md') {
      // Use URLs only in the readme.
      return `https://example.com/rules/${name}.html`;
    }
  },
};

module.exports = config;

Badges

While emojis are the recommended representations of configs that a rule belongs to, you can alternatively use a text/image/icon badge for configs by supplying the following markdown for the emoji using the --config-emoji option.

For example, here's the markdown for a text badge representing a custom fun config that displays in blue (note that the markdown includes alt text followed by the image URL):

![fun config badge](https://img.shields.io/badge/-fun-blue.svg)

Here's how you'd configure it:

/** @type {import('eslint-doc-generator').GenerateOptions} */
const config = {
  configEmoji: [
    ['fun', '![fun config badge](https://img.shields.io/badge/-fun-blue.svg)'],
  ],
};

module.exports = config;

And how it looks:

Compatibility

Build tools

If you have a build step for your code like Babel or TypeScript, you may need to adjust your scripts to run your build before this tool to ensure the documentation is generated from the latest plugin information:

{
  "build": "tsc",
  "update:eslint-docs": "npm run build && eslint-doc-generator"
}

markdownlint

The output of this tool should be compatible with the default configuration of markdownlint, which you might use to lint your markdown. If it's not, you can follow the prettier example to tweak your scripts or use the postprocess option. See here for an example of markdownlint's Node API for applying fixes to use in your postprocess function.

prettier

If you use prettier to format your markdown, you can provide a postprocess function to ensure the documentation generated by this tool is formatted correctly:

const prettier = require('prettier');
const { prettier: prettierRC } = require('./package.json'); // or wherever your prettier config lies

/** @type {import('eslint-doc-generator').GenerateOptions} */
const config = {
  postprocess: (content, path) =>
    prettier.format(content, { ...prettierRC, parser: 'markdown' }),
};

module.exports = config;

Alternatively, you can configure your scripts to run prettier after this tool:

{
  "format": "prettier --write .",
  "lint:eslint-docs": "npm run update:eslint-docs && git diff --exit-code",
  "update:eslint-docs": "eslint-doc-generator && npm run format"
}

Semantic versioning policy

This tool follows semantic versioning.

New features will be released as a minor version, while bug fixes will be released as a patch version.

Breaking changes will be released as a major version and include:

• Changing an option default
• Renaming or removing an option
• Other backwards-incompatible changes to the CLI / API
• Raising Node or ESLint version requirements

Tweaks to the generated documentation output can take place in any type of release including minor and patch versions. This can break your build, as even a small formatting change will cause a diff, but you can simply re-run the tool to fix.

Related

• eslint-plugin-eslint-plugin - Linter for ESLint plugins (related list)
• generator-eslint - Generates initial ESLint plugin and rule files but without the sophisticated documentation provided by eslint-doc-generator