depcheck
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    1.4.2 • Public • Published

    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

    Build Status Financial Contributors on Open Collective Build status codecov.io

    dependencies Status devDependencies Status

    Installation

    npm install -g depcheck
    

    Or simply using npx which is a package runner bundled in npm:

    $ npx depcheck
    

    Notice: depcheck needs node.js >= 10.

    Syntax Support

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

    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
    • serverless- Serverless plugins

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

    --ignore-path: Path to a file with patterns describing files to ignore. Files must match the .gitignore spec. Example, --ignore-path=.eslintignore.

    --ignore-patterns: Comma separated patterns describing files to ignore. Patterns must match the .gitignore spec. Example, --ignore-patterns=build/Release,dist,coverage,*.log.

    --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.

    --config=[filename]: An external configuration file (see below).

    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
      ignorePatterns: [
        // files matching these patterns 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).then((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].

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    License

    MIT License.

    Install

    npm i depcheck

    DownloadsWeekly Downloads

    224,224

    Version

    1.4.2

    License

    MIT

    Unpacked Size

    212 kB

    Total Files

    79

    Last publish

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