title	description
npm-package-json-lint configuration in MegaLinter	How to use npm-package-json-lint (configure, ignore files, ignore errors, help & version documentations) to analyze JSON files

npm-package-json-lint

npm-package-json-lint is a specialized linter designed specifically for npm package.json files that ensures consistency, correctness, and adherence to best practices in Node.js project configuration. It serves as an essential tool for maintaining professional npm package standards.

Key Features:

Package.json Focused: Specialized validation specifically for npm package.json structure and content
Comprehensive Rule Set: Extensive collection of rules covering dependencies, metadata, scripts, and package configuration
Best Practices Enforcement: Validates against npm and Node.js ecosystem best practices and conventions
Configurable Validation: Highly customizable rules through .npmpackagejsonlintrc.json configuration files
Dependency Analysis: Checks for missing dependencies, version format consistency, and dependency organization
Metadata Validation: Ensures required fields like name, version, description are present and properly formatted
Script Analysis: Validates npm scripts for common patterns and potential issues
Multi-Project Support: Handles monorepos and complex project structures with hierarchical configuration

npm-package-json-lint documentation

Version in MegaLinter: 9.0.0
Visit Official Web Site{target=_blank}
See How to configure npm-package-json-lint rules{target=_blank}
- If custom .npmpackagejsonlintrc.json config file isn't found, .npmpackagejsonlintrc.json{target=_blank} will be used
See How to ignore files and directories with npm-package-json-lint{target=_blank}
- You can define a .npmpackagejsonlintignore file to ignore files and folders
See Index of problems detected by npm-package-json-lint{target=_blank}

{target=_blank}

Configuration in MegaLinter

Enable npm-package-json-lint by adding JSON_NPM_PACKAGE_JSON_LINT in ENABLE_LINTERS variable
Disable npm-package-json-lint by adding JSON_NPM_PACKAGE_JSON_LINT in DISABLE_LINTERS variable

Variable	Description	Default value
JSON_NPM_PACKAGE_JSON_LINT_ARGUMENTS	User custom arguments to add in linter CLI call Ex: `-s --foo "bar"`
JSON_NPM_PACKAGE_JSON_LINT_COMMAND_REMOVE_ARGUMENTS	User custom arguments to remove from command line before calling the linter Ex: `-s --foo "bar"`
JSON_NPM_PACKAGE_JSON_LINT_CLI_LINT_MODE	Override default CLI lint mode ⚠️ As default value is project, overriding might not work - `file`: Calls the linter for each file - `list_of_files`: Call the linter with the list of files as argument - `project`: Call the linter from the root of the project	`project`
JSON_NPM_PACKAGE_JSON_LINT_FILE_EXTENSIONS	Allowed file extensions. `"*"` matches any extension, `""` matches empty extension. Empty list excludes all files Ex: `[".py", ""]`	`[".json"]`
JSON_NPM_PACKAGE_JSON_LINT_FILE_NAMES_REGEX	File name regex filters. Regular expression list for filtering files by their base names using regex full match. Empty list includes all files Ex: `["Dockerfile(-.+)?", "Jenkinsfile"]`	`["package\\.json"]`
JSON_NPM_PACKAGE_JSON_LINT_PRE_COMMANDS	List of bash commands to run before the linter	None
JSON_NPM_PACKAGE_JSON_LINT_POST_COMMANDS	List of bash commands to run after the linter	None
JSON_NPM_PACKAGE_JSON_LINT_UNSECURED_ENV_VARIABLES	List of env variables explicitly not filtered before calling JSON_NPM_PACKAGE_JSON_LINT and its pre/post commands	None
JSON_NPM_PACKAGE_JSON_LINT_CONFIG_FILE	npm-package-json-lint configuration file name Use `LINTER_DEFAULT` to let the linter find it	`.npmpackagejsonlintrc.json`
JSON_NPM_PACKAGE_JSON_LINT_RULES_PATH	Path where to find linter configuration file	Workspace folder, then MegaLinter default rules
JSON_NPM_PACKAGE_JSON_LINT_DISABLE_ERRORS	Run linter but consider errors as warnings	`false`
JSON_NPM_PACKAGE_JSON_LINT_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	`0`
JSON_NPM_PACKAGE_JSON_LINT_CLI_EXECUTABLE	Override CLI executable	`['npmPkgJsonLint']`

MegaLinter Flavors

This linter is available in the following flavors

Flavor	Description	Embedded linters
all	Default MegaLinter Flavor	127
cupcake	MegaLinter for the most commonly used languages	88
dotnet	Optimized for C, C++, C# or VB based projects	64
dotnetweb	Optimized for C, C++, C# or VB based projects with JS/TS	73
javascript	Optimized for JAVASCRIPT or TYPESCRIPT based projects	59
salesforce	Optimized for Salesforce based projects	53

Behind the scenes

How are identified applicable files

Activated only if one of these files is found: package.json
File extensions: .json
File names (regex): package\.json

How the linting is performed

npm-package-json-lint is called once on the whole project directory (project CLI lint mode)

filtering can not be done using MegaLinter configuration variables,it must be done using npm-package-json-lint configuration or ignore file (if existing)
VALIDATE_ALL_CODEBASE: false doesn't make npm-package-json-lint analyze only updated files

Example calls

npmPkgJsonLint .

npmPkgJsonLint --configFile .npmpackagejsonlintrc.json .

Help content

  Configurable linter for package.json files.

  Usage
    $ npmPkgJsonLint <patterns>

  Options
    --quiet, -q Report errors only
    --noConfigFiles, -ncf Disables use of .npmpackagejsonlintrc.json files, npmpackagejsonlint.config.js files, and npmpackagejsonlint object in package.json file.
    --configFile, -c File path of .npmpackagejsonlintrc.json
    --ignorePath, -i Path to a file containing patterns that describe files to ignore. The path can be absolute or relative to process.cwd(). By default, npm-package-json-lint looks for .npmpackagejsonlintignore in process.cwd().
    --maxWarnings, -mw Maximum number of warnings that can be detected before an error is thrown.
    --allowEmptyTargets Do not throw an error when a list of targets is empty.

  Examples
    $ npmPkgJsonLint --version
    $ npmPkgJsonLint .
    $ npmPkgJsonLint ./packages
    $ npmPkgJsonLint ./package1 ./package2
    $ npmPkgJsonLint -c ./config/.npmpackagejsonlintrc.json .
    $ npmPkgJsonLint --configFile ./config/npmpackagejsonlint.config.json .
    $ npmPkgJsonLint -q .
    $ npmPkgJsonLint --quiet ./packages
    $ npmPkgJsonLint . --ignorePath .gitignore
    $ npmPkgJsonLint . -i .gitignore
    $ npmPkgJsonLint . --maxWarnings 10
    $ npmPkgJsonLint . -mw 10

Installation on mega-linter Docker image

Dockerfile commands :

# renovate: datasource=npm depName=npm-package-json-lint
ARG NPM_PACKAGE_JSON_LINT_VERSION=9.0.0
# renovate: datasource=npm depName=npm-package-json-lint-config-default
ARG NPM_PACKAGE_JSON_LINT_CONFIG_DEFAULT_VERSION=8.0.1

NPM packages (node.js):
- npm-package-json-lint@9.0.0
- npm-package-json-lint-config-default@8.0.1

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