eslint-plugin-codegen
Advanced tools
An eslint plugin for inline codegen. Auto-fixes out of sync code, with presets for barrels, jsdoc to markdown and more.
An eslint plugin for inline codegen. Auto-fixes out of sync code, with presets for barrels, jsdoc to markdown and more.
Sometimes the same information is useful in multiple places - for example, jsdoc comments in code can double as markdown-formatted documentation for a library.
This allows generating code in a project using eslint, without having to incorporate any extra build tools, either for the codegen itself, or to validate that the generated code is up to date. So references to other parts of the project will always stay up to date - and your existing CI tools can enforce this just by running eslint.
Here's an example of it being used along with VSCode's eslint plugin, with auto-fix-on-save:
Before you use this, note that it's still in v0. That means:
markdownFromJsdoc only works with export const ... style exports. Currently most of the features implemented are ones that are specifically needed for this git repo.In an eslint-enabled project, install with
npm install --save-dev eslint-plugin-codegen
or
yarn add --dev eslint-plugin-codegen
Then add the plugin and rule to your eslint config, for example in eslintrc.js:
module.exports = {
//...
plugins: [
// ...
'codegen',
],
rules: {
// ...
'codegen/codegen': 'error',
},
}
You can use the rule by running eslint in a standard way, with something like this in an npm script: eslint --ext .ts,.js,.md .
In vscode, if using the eslint plugin, you may need to tell it to validate markdown files in your repo's .vscode/settings.json file (see this repo for an example):
{
"eslint.validate": ["markdown", "javascript", "typescript"],
"editor.codeActionsOnSave": {
"source.fixAll.eslint": true
}
}
To trigger the rule, add a comment line to a source file.
In markdown:
<!-- codegen:start {{ OPTIONS }} -->
In typescript/javascript:
// codegen:start {{ OPTIONS }}
Where {{ OPTIONS }} are an inline object in the format:
{preset: presetName, key1: value1, key2: value2}
Where key1 and key2 are options passed to the codegen preset. yaml is used to parse the object, So any valid yaml that fits on one line can be passed as options. In practise, the one-line restriction means using yaml's "flow style" for collections.
See below for documentation. This repo also has lots of usage examples.
This plugin uses an ESLint processor to handle markdown and YAML files. ESLint only allows one processor per file type, so the processor from this plugin is designed to be compatible with eslint-plugin-markdown. But to use both plugins, you need to use the process for eslint-plugin-codegen, not eslint-plugin-markdown. You can do this by adding the recommended config for eslint-plugin-codegen second, e.g.
module.exports = {
plugins: ['markdown', 'codegen'],
extends: ['plugin:markdown/recommended', 'plugin:codegen/recommended'],
}
Or specify the processor explicitly - when you switch to flat config this will be required:
module.exports = {
// 1. Add the plugin.
plugins: ['markdown'],
overrides: [
{
// 2. Enable the Markdown processor for all .md files.
files: ['**/*.md'],
processor: 'codegen/processor', // NOT 'markdown/markdown'
},
],
}
Define your own codegen function, which will receive all options specified. Import the Preset type from this library to define a strongly-typed preset function:
export const jsonPrinter: import('eslint-plugin-codegen').Preset<{myCustomProp: string}> = ({meta, options}) => {
const components = meta.glob('**\/*.tsx') // uses 'globSync' from glob package
const json = JSON.stringify({filename: meta.filename, customProp: options.myCustomProp, components}, null, 2)
return `export default ${json}`
}
// codegen:start {export: jsonPrinter}
This can be used in other files by specifying the source option like:
<!-- codegen:start {source: ./lib/my-custom-preset.js, export: jsonPrinter, myCustomProp: hello}
Note that some helpers passed via dependencies, such as glob, fs, path, child_process, lodash, jsYaml, dedent, and readPkgUp, corresponding to those node modules respectively. These can be useful to allow access to those libraries without them being production dependencies. This also allows your lint process to use these node-only dependencies, even in a file that is not run in node - only the calls would be included in any bundled output, not the dependencies themselves.
| name | description |
|---|---|
| source | Relative path to the module containing the custom preset. Default: the file being linted. |
| export | The name of the export. If omitted, the module's default export should be a preset function. |
| require | A module to load before source. If not set, defaults to tsx/cjs or ts-node/register/transpile-only for typescript sources. |
| dev | Set to true to clear the require cache for source before loading. Allows editing the function without requiring an IDE reload. Default false if the CI enviornment variable is set, true otherwise. |
Sometimes, you may want to write a custom function that takes a long time to run. To avoid having to wait for it to run every time you lint, you can set the dev option to true. This will clear the require cache for the custom function, so it will be run fresh each time.
export const longRunningFunction: import('eslint-plugin-codegen').Preset = ({cache}) => {
const result = cache({maxAge: '1 year'}, () => {
// do something that takes a long time to run, but doesn't need to run too often
})
return result
}
// codegen:start {preset: custom, export: longRunningFunction}
You can use some helpers that are passed to the preset function:
export const secretaryGeneralLogStatement: import('eslint-plugin-codegen').Preset = ({cache, dependencies}) => {
const result = cache({maxAge: '1 year'}, () => {
const res = dependencies.fetchSync('https://www.un.org/sg')
const secretaryGeneral = (/Secretary-General ([A-Z].+?) [a-z]/.exec(res.text))?.[1]
return `console.log('The UN Secretary-General is ${secretaryGeneral}')`
})
return result
}
// codegen:start {preset: custom, export: secretaryGeneralLogStatement}
This will transform to something like:
export const secretaryGeneralLogStatement: import('eslint-plugin-codegen').Preset = ({cache, dependencies}) => {
return cache({maxAge: '4 weeks'}, () => {
const res = dependencies.fetchSync('https://en.wikipedia.org/wiki/Secretary-General_of_the_United_Nations')
const $ = dependencies.cheerio.load(res.text)
const incumbent = $('.infobox div:contains("Incumbent")')
const secretaryGeneral = incumbent.find('a').text()
return `console.log('The UN Secretary-General is ${secretaryGeneral}')`
})
return result
}
// codegen:start {preset: custom, export: secretaryGeneralLogStatement}
// codegen:hash {input: 4119892f2e6eaf56ae5c346de91be718, output: eed0d07c81b82bff1d3e4751073b0112, timestamp: 2025-03-05T18:58:13.921Z}
console.log('The UN Secretary-General is António Guterres')
// codegen:end
It will not re-run unless the input has changed, the output hash doesn't match, or until 1 year after the recorded timestamp. "The input" is a hash of the following:
codegen:start and codegen:end directivesThe output (i.e. the generated code between the start and end directives) is also hashed and written to the hash directive.
If the the generated code doesn't match the output hash, the generator function will re-run.
This means that if you change the filename, or any of the source code, it will re-run. You can control this behaviour when defining your generator function:
export const secretaryGeneralLogStatement: import('eslint-plugin-codegen').Preset =
({cache, dependencies}) => {
return cache({maxAge: '4 weeks'}, () => {
const res = dependencies.fetchSync(
'https://en.wikipedia.org/wiki/Secretary-General_of_the_United_Nations',
)
const $ = dependencies.cheerio.load(res.text)
const incumbent = $('.infobox div:contains("Incumbent")')
const secretaryGeneral = incumbent.find('a').text()
return `console.log('The UN Secretary-General is ${secretaryGeneral}')`
})
}
// codegen:start {preset: custom, export: secretaryGeneralLogStatement}
// codegen:hash {input: 4119892f2e6eaf56ae5c346de91be718, output: eed0d07c81b82bff1d3e4751073b0112, timestamp: 2025-03-05T18:58:13.921Z}
console.log('The UN Secretary-General is António Guterres')
// codegen:end
The helpers that are provided to the generator function via the dependencies prop are listed below. You can use all of them in a type-safe way in your generator function, without having to add them as dependencies or even devDependencies:
fs: https://nodejs.org/api/fs.htmlpath: https://nodejs.org/api/path.htmlchild_process: https://nodejs.org/api/child_process.htmllodash: https://npmjs.com/package/lodashjsYaml: https://npmjs.com/package/js-yamldedent: https://npmjs.com/package/dedentglob: https://npmjs.com/package/globreadPkgUp: https://npmjs.com/package/read-pkg-upcheerio: https://npmjs.com/package/cheeriomakeSynchronous: A function for making functions synchronous by running them in a subprocess. See the code for more details. It's a simplified version of this. Note: it's strongly recommended to use this with the cache feature to avoid slowing down your lint process.fetchSync: A simplified fetch wrapper that runs synchronously via makeSynchronous. See the code for more details. Useful for fetching data from the internet without adding a production dependency. Note: it's strongly recommended to use this with the cache feature to avoid slowing down your lint process.The plugin will attempt to run generator functions written in typescript. If tsx or ts-node are available, they will be used to register their respective loaders before requiring the file containing the generator function. If you have trouble, try installing tsx even if you don't otherwise use it - or just write the generator function in a separate javascript file.
Note: to get type safety for the helpers in javascript files, use the {@type ...} syntax:
/** @type {import('eslint-plugin-codegen').Preset} */
module.exports.myGenerator = ({dependencies}) => {
const subpackages = dependencies.glob.sync('subpackages/**/*.package.json')
return `const subpackages = ${JSON.stringify(subpackages)}`
}
Bundle several modules into a single convenient one.
// codegen:start {preset: barrel, include: some/path/*.ts, exclude: some/path/*util.ts}
export * from './some/path/module-a'
export * from './some/path/module-b'
export * from './some/path/module-c'
// codegen:end
| name | description |
|---|---|
| include | [optional] If specified, the barrel will only include file paths that match this glob pattern |
| exclude | [optional] If specified, the barrel will exclude file paths that match these glob patterns |
| import | [optional] If specified, matching files will be imported and re-exported rather than directly exported with export * from './xyz'. Use import: star for import * as xyz from './xyz' style imports.Use import: default for import xyz from './xyz' style imports. |
| export | [optional] Only valid if the import style has been specified (either import: star or import: default).If specified, matching modules will be bundled into a const or default export based on this name. If set to {name: someName, keys: path} the relative file paths will be used as keys. Otherwise the file pathswill be camel-cased to make them valid js identifiers. |
| extension | [optional] Useful for ESM modules. If set to true files will be imported with the file extension. If set to an object, extensions will be converted using this object. |
Convert jsdoc for an es export from a javascript/typescript file to markdown.
<!-- codegen:start {preset: markdownFromJsdoc, source: src/foo.ts, export: bar} -->
| name | description |
|---|---|
| source | {string} relative file path containing the export with jsdoc that should be copied to markdown |
| export | {string} the name of the export |
| headerLevel | {1 |
Generate a table of contents for a monorepo.
<!-- codegen:start {preset: monorepoTOC} -->
<!-- codegen:start {preset: monorepoTOC, repoRoot: .., workspaces: lerna, filter: {package.name: foo}, sort: -readme.length} -->
| name | description |
|---|---|
| repoRoot | [optional] the relative path to the root of the git repository. By default, searches parent directories for a package.json to find the "root". |
| filter | [optional] a dictionary of filter rules to whitelist packages. Filters can be applied based on package.json keys, examples: - filter: '@myorg/.*-lib' (match packages with names matching this regex)- filter: { package.name: '@myorg/.*-lib' } (equivalent to the above)- filter: { package.version: '^[1-9].*' } (match packages with versions starting with a non-zero digit, i.e. 1.0.0+)- filter: '^(?!.*(internal$))' (match packages that do not contain "internal" anywhere (using negative lookahead))- filter: { package.name: '@myorg', path: 'libraries' } (match packages whose name contains "@myorg" and whose path matches "libraries")- filter: { readme: 'This is production-ready' } (match packages whose readme contains the string "This is production-ready") |
| sort | [optional] sort based on package properties (see filter), or readme length. Use - as a prefix to sort descending.examples: - sort: package.name (sort by package name)- sort: -readme.length (sort by readme length, descending)- sort: toplogical (sort by toplogical dependencies, starting with the most depended-on packages) |
Convert jsdoc to an es export from a javascript/typescript file to markdown.
<!-- codegen:start {preset: markdownFromJsdoc, source: src/foo.ts, export: bar} -->
| name | description |
|---|---|
| source | {string} relative file path containing the export with jsdoc that should be copied to markdown |
| export | {string} the name of the export |
Generate a table of contents from the current markdown file, based on markdown headers (e.g. ### My section title)
<!-- codegen:start {preset: markdownTOC, minDepth: 2, maxDepth: 5} -->
| name | description |
|---|---|
| minDepth | exclude headers with lower "depth". e.g. if set to 2, # H1 would be excluded but ## H2 would be included. @default 2 |
| maxDepth | exclude headers with higher "depth". e.g. if set to 3, #### H4 would be excluded but ### H3 would be included. @default Infinity |
Use a test file to generate library usage documentation. Note: this has been tested with vitest and jest. It might also work fine with mocha, and maybe ava, but those haven't been tested. JSDoc/inline comments above tests will be added as a "preamble", making this a decent way to quickly document API usage of a library, and to be sure that the usage is real and accurate.
<!-- codegen:start {preset: markdownFromTests, source: test/foo.test.ts, headerLevel: 3} -->
| name | description |
|---|---|
| source | the test file |
| include | if defined, only tests with titles matching one of these regexes will be included |
| exclude | if defined, tests with titles matching one of these regexes will be excluded |
| headerLevel | The number of # characters to prefix each title with |
| includeEslintDisableDirectives | If true, // eslint-disable ... type comments will be included in the preamble. @default false |
Generates a yaml config for the GitHub Pull Request Labeler Action. Creates a label per package name, which will be applied to any file modified under the leaf package path. When packages are added or removed from the repo, or renamed, the yaml config will stay in sync with them. Additional labels can be added outside of the generated code block. See https://github.com/mmkal/ts/tree/main/.github/labeler.yml for an example.
# codegen:start {preset: labeler}
Note: eslint and related tools make it quite difficult to lint github action yaml files. To get it working, you'll need to:
'!.github' to your .eslintignore file, or the ignorePatterns property in your lint config."yaml" to the "eslint.validate" list in vscode/settings.json.'.yml' (and/or '.yaml') to the parserOptions.extraFileExtensions list in your lint config..) in your tsconfig. See https://github.com/mmkal/ts/tree/main/tsconfig.eslint.json for an example.| name | description |
|---|---|
| repoRoot | [optional] path to the repository root. If not specified, the rule will recursively search parent directories for package.json files |
In addition to the custom preset, you can also define your own presets in eslint configuration, e.g.:
module.exports = {
// ...
plugins: [
// ...
'codegen',
],
rules: {
// ...
'codegen/codegen': ['error', {presets: require('./-presets')}],
},
}
presets should be a record of preset functions, conforming to the Preset interface from this package. This can be used to extend the in-built ones. For example, you could make generated markdown collapsible:
Before:
<!-- codegen:start {preset: markdownTOC}-->
- [Section1](#section1)
- [Section2](#section2)
<!-- codeg```
`my-custom-presets.js`:
<!-- eslint-disable @typescript-eslint/no-var-requires -->
<!-- eslint-disable import/no-extraneous-dependencies -->
```js
const {presets} = require('eslint-plugin-codegen')
module.exports.markdownTOC = params => {
const toc = presets.markdownTOC(params)
return [
'<details>',
'<summary>click to expand</summary>',
'',
toc,
'</details>',
].join('\n')
}
.eslintrc.js:
module.exports = {
// ...
plugins: [
// ...
'codegen',
],
rules: {
// ...
'codegen/codegen': ['error', {presets: require('./my-custom-presets')}],
},
}
After:
readme.md:
<!-- codegen:start {preset: markdownTOC}-->
<details>
<summary>click to expand</summary>
- [Section1](#section1)
- [Section2](#section2)
</details>
<!-- codegen:end -->
Rendered:
The code in this repository was moved from https://github.com/mmkal/ts
FAQs
An eslint plugin for inline codegen. Auto-fixes out of sync code, with presets for barrels, jsdoc to markdown and more.
The npm package eslint-plugin-codegen receives a total of 4,322 weekly downloads. As such, eslint-plugin-codegen popularity was classified as popular.
We found that eslint-plugin-codegen demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Research
Security News
Malicious PyPI package ‘set-utils’ steals Ethereum private keys by exfiltrating them through blockchain transactions via the Polygon RPC.
Research
Security News
Malicious Go packages are impersonating popular libraries to install hidden loader malware on Linux and macOS, targeting developers with obfuscated payloads.
Security News
Bybit's $1.46B hack by North Korea's Lazarus Group pushes 2025 crypto losses to $1.6B in just two months, already surpassing all of 2024's $1.49B total.