depcheck

What is depcheck?

depcheck is a tool that helps you to find unused dependencies in your project. It scans your project files and identifies which dependencies are not being used, which can help you to clean up your package.json file and reduce the size of your project.

What are depcheck's main functionalities?

Check for unused dependencies

This feature allows you to check for unused dependencies in your project. You can specify options to ignore certain directories or dependencies that match specific patterns.

const depcheck = require('depcheck');

const options = {
  ignoreDirs: [
    'sandbox',
    'dist',
    'bower_components'
  ],
  ignoreMatches: [
    'grunt-*'
  ]
};

depcheck('/path/to/your/project', options, (unused) => {
  console.log(unused.dependencies); // an array containing the unused dependencies
  console.log(unused.devDependencies); // an array containing the unused devDependencies
});

Check for missing dependencies

This feature allows you to check for dependencies that are used in your project but are not listed in your package.json file.

const depcheck = require('depcheck');

depcheck('/path/to/your/project', {}, (unused) => {
  console.log(unused.missing); // a lookup containing the dependencies missing in package.json but used in the code
});

Check for invalid files

This feature allows you to identify files in your project that could not be parsed, which might indicate issues with those files.

const depcheck = require('depcheck');

depcheck('/path/to/your/project', {}, (unused) => {
  console.log(unused.invalidFiles); // a lookup containing the files that could not be parsed
});

Other packages similar to depcheck

npm-check

npm-check is a similar tool that checks for outdated, incorrect, and unused dependencies. It provides a more interactive experience compared to depcheck, allowing you to update and uninstall packages directly from the command line.

dependency-check

dependency-check is another tool that checks for missing or unused dependencies. It is more focused on ensuring that all dependencies are correctly listed in your package.json file, rather than identifying unused dependencies.

madge

madge is a tool that provides a visual representation of your project's dependency graph. While it does not specifically focus on unused dependencies, it can help you understand the structure of your project and identify potential issues.

README

depcheck

Depcheck is a tool for analyzing the dependencies in a project to see: how each dependency is used, which dependencies are useless, and which dependencies are missing from package.json.

Status

Installation

npm install -g depcheck

Notice: depcheck needs node.js >= 10.

Syntax Support

Depcheck not only recognizes the dependencies in JavaScript files, but also supports these syntaxes:

• JavaScript (ES5, ES6 and ES7)
• React JSX
• CoffeeScript
• Typescript (with typescript dependency)
• SASS and SCSS (with node-sass dependency)
• Vue.js (with vue-template-compiler dependency)

To get the syntax support by external dependency, please install the corresponding package explicitly. For example, for Typescript user, install depcheck with typescript package:

npm install -g depcheck typescript

Special

The special component is used to recognize the dependencies that are not generally used in the above syntax files. The following scenarios are supported by specials:

• babel - Babel presets and plugins
• bin - Dependencies used in npm commands, Travis scripts or other CI scripts
• commitizen - Commitizen configuration adaptor
• eslint - ESLint configuration presets, parsers and plugins
• feross-standard - Feross standard format parser
• gatsby - Gatsby configuration parser
• gulp-load-plugins - Gulp-load-plugins lazy loaded plugins
• husky - Husky configuration parser
• istanbul - Istanbul nyc configuration extensions
• jest - Jest properties in Jest Configuration
• karma - Karma configuration frameworks, browsers, preprocessors and reporters
• lint-staged - Lint-staged configuration parser
• mocha - Mocha explicit required dependencies
• prettier - Prettier configuration module
• tslint - TSLint configuration presets, parsers and plugins
• ttypescript - ttypescript transformers
• webpack - Webpack loaders

The logic of a special is not perfect. There might be false alerts. If this happens, please open an issue for us.

Usage

depcheck [directory] [arguments]

The directory argument is the root directory of your project (where the package.json file is). If unspecified, defaults to current directory.

All of the arguments are optional:

--ignore-bin-package=[true|false]: A flag to indicate if depcheck ignores the packages containing bin entry. The default value is false.

--skip-missing=[true|false]: A flag to indicate if depcheck skips calculation of missing dependencies. The default value is false.

--json: Output results in JSON. When not specified, depcheck outputs in human friendly format.

--ignores: A comma separated array containing package names to ignore. It can be glob expressions. Example, --ignores="eslint,babel-*".

--ignore-dirs: A comma separated array containing directory names to ignore. Example, --ignore-dirs=dist,coverage.

--help: Show the help message.

--parsers, --detectors and --specials: These arguments are for advanced usage. They provide an easy way to customize the file parser and dependency detection. Check the pluggable design document for more information.

Usage with a configuration file

Depcheck can be used with an rc configuration file. In order to do so, create a .depcheckrc file in your project's package.json folder, and set the CLI keys in YAML, JSON, and Javascript formats. For example, the CLI arguments --ignores="eslint,babel-*" --skip-missing=true would turn into:

.depcheckrc

ignores: ["eslint", "babel-*"]
skip-missing: true

Important: if provided CLI arguments conflict with configuration file ones, the CLI ones will take precedence over the rc file ones.

The rc configuration file can also contain the following extensions: .json, .yaml, .yml.

API

Similar options are provided to depcheck function for programming:

import depcheck from 'depcheck';

const options = {
  ignoreBinPackage: false, // ignore the packages with bin entry
  skipMissing: false, // skip calculation of missing dependencies
  ignoreDirs: [
    // folder with these names will be ignored
    'sandbox',
    'dist',
    'bower_components',
  ],
  ignoreMatches: [
    // ignore dependencies that matches these globs
    'grunt-*',
  ],
  parsers: {
    // the target parsers
    '*.js': depcheck.parser.es6,
    '*.jsx': depcheck.parser.jsx,
  },
  detectors: [
    // the target detectors
    depcheck.detector.requireCallExpression,
    depcheck.detector.importDeclaration,
  ],
  specials: [
    // the target special parsers
    depcheck.special.eslint,
    depcheck.special.webpack,
  ],
  package: {
    // may specify dependencies instead of parsing package.json
    dependencies: {
      lodash: '^4.17.15',
    },
    devDependencies: {
      eslint: '^6.6.0',
    },
    peerDependencies: {},
    optionalDependencies: {},
  },
};

depcheck('/path/to/your/project', options, (unused) => {
  console.log(unused.dependencies); // an array containing the unused dependencies
  console.log(unused.devDependencies); // an array containing the unused devDependencies
  console.log(unused.missing); // a lookup containing the dependencies missing in `package.json` and where they are used
  console.log(unused.using); // a lookup indicating each dependency is used by which files
  console.log(unused.invalidFiles); // files that cannot access or parse
  console.log(unused.invalidDirs); // directories that cannot access
});

Example

The following example checks the dependencies under /path/to/my/project folder:

$> depcheck /path/to/my/project
Unused dependencies
* underscore
Unused devDependencies
* jasmine
Missing dependencies
* lodash

It figures out:

• The dependency underscore is declared in the package.json file, but not used by any code.
• The devDependency jasmine is declared in the package.json file, but not used by any code.
• The dependency lodash is used somewhere in the code, but not declared in the package.json file.

Please note that, if a subfolder has a package.json file, it is considered another project and should be checked with another depcheck command.

The following example checks the same project, however, outputs as a JSON blob. Depcheck's JSON output is in one single line for easy pipe and computation. The json command after the pipe is a node.js program to beautify the output.

$> depcheck /path/to/my/project --json | json
{
  "dependencies": [
    "underscore"
  ],
  "devDependencies": [
    "jasmine"
  ],
  "missing": {
    "lodash": [
      "/path/to/my/project/file.using.lodash.js"
    ]
  },
  "using": {
    "react": [
      "/path/to/my/project/file.using.react.jsx",
      "/path/to/my/project/another.file.using.react.jsx"
    ],
    "lodash": [
      "/path/to/my/project/file.using.lodash.js"
    ]
  },
  "invalidFiles": {
    "/path/to/my/project/file.having.syntax.error.js": "SyntaxError: <call stack here>"
  },
  "invalidDirs": {
    "/path/to/my/project/folder/without/permission": "Error: EACCES, <call stack here>"
  }
}

• The dependencies, devDependencies and missing properties have the same meanings in the previous example.
• The using property is a lookup indicating each dependency is used by which files.
• The value of missing and using lookup is an array. It means the dependency may be used by many files.
• The invalidFiles property contains the files having syntax error or permission error. The value is the error details. However, only one error is stored in the lookup.
• The invalidDirs property contains the directories having permission error. The value is the error details.

False Alert

Depcheck just walks through all files and tries to find the dependencies according to some predefined rules. However, the predefined rules may not be enough or may even be wrong.

There may be some cases in which a dependency is being used but is reported as unused, or a dependency is not used but is reported as missing. These are false alert situations.

If you find that depcheck is reporting a false alert, please open an issue with the following information to let us know:

• The output from depcheck --json command. Beautified JSON is better.
• Which dependencies are considered as false alert?
• How are you using those dependencies, what do the files look like?

Changelog

We use the GitHub release page to manage changelog.

Contributors

Code Contributors

This project exists thanks to all the people who contribute. [Contribute].

Financial Contributors

Become a financial contributor and help us sustain our community. [Contribute]

Individuals

Organizations

Support this project with your organization. Your logo will show up here with a link to your website. [Contribute]

License

MIT License.

Changelog

0.9.2 (2020-01-30)

Full Changelog

Closed issues:

• Use Cosmiconfig #516
• Feature: add special parser for Istanbul.js #508
• New mocha configuration file not seen #507
• False positive with @types/mocha #504
• Error: ENFILE: file table overflow (macOS) #501
• eslint: dependency wrongly mark as unused #500
• special/eslint: bad calculation of preset dependencies #476
• Load ignore rules from a lines separated file #409
• Improvements for CI use #162

Merged pull requests:

• Review special documentation #515 (sveyret)
• Add Istanbul special parser #514 (sveyret)
• Refactor: read content only when needed #513 (znarf)
• Add debug package and messages to the project #512 (znarf)
• Support for more decorators #511 (micky2be)
• Improve recursive work of eslint configuration check #506 (sveyret)
• Improvements for mocha #505 (sveyret)
• Support webpack styleguidist configuration #503 (znarf)
• Use a single promise to read a given file #502 (znarf)
• Support for next.js webpack configuration #496 (znarf)
• Rename 'linters' and fix babel config file detection #495 (znarf)
• Suppress unnecessary fileContent #494 (znarf)
• Update travis commands and reference #493 (znarf)
• Add eslint-plugin-mocha and lint test directory #492 (znarf)
• Better prettier configuration #490 (znarf)
• Remove remaining dev option #489 (znarf)
• chore: remove editorconfig file #488 (rumpl)
• Update babel target to node 10, use prettier plugin #487 (rumpl)
• chore(deps): Update all dependencies to latest #486 (rumpl)
• Do not calculate expensive dep differences when skipMissing is active #485 (dword-design)
• Adjust babel special to eslint implementation #484 (dword-design)
• Add deps parameter to detectors #482 (dword-design)
• Activating Open Collective #481 (monkeywithacupcake)
• Document and provide types for the API's package option #479 (edsrzf)
• Try to load eslint.js modules without a module.exports wrapper #478 (rjatkins)
• special/eslint: corrections on dependencies resolver #477 (sveyret)
• chore: add changelog file #475 (rumpl)
• Support loading configuration from a config file. #408 (Urik)