eslint

eslint requires a custom configuration file applicable to your project.

You can create it by typing npx eslint --init in the root of your repository

eslint documentation

Version in MegaLinter: 8.42.0
Visit Official Web Site
See How to configure eslint rules
See How to disable eslint rules in files
See How to ignore files and directories with eslint
- You can define a .eslintignore file to ignore files and folders
See Index of problems detected by eslint

Configuration in MegaLinter

Enable eslint by adding JAVASCRIPT_ES in ENABLE_LINTERS variable
Disable eslint by adding JAVASCRIPT_ES in DISABLE_LINTERS variable

Enable autofixes by adding JAVASCRIPT_ES in APPLY_FIXES variable

Variable	Description	Default value
JAVASCRIPT_ES_ARGUMENTS	User custom arguments to add in linter CLI call Ex: `-s --foo "bar"`
JAVASCRIPT_ES_FILTER_REGEX_INCLUDE	Custom regex including filter Ex: `(src\\|lib)`	Include every file
JAVASCRIPT_ES_FILTER_REGEX_EXCLUDE	Custom regex excluding filter Ex: `(test\\|examples)`	Exclude no file
JAVASCRIPT_ES_CLI_LINT_MODE	Override default CLI lint mode - `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	`list_of_files`
JAVASCRIPT_ES_FILE_EXTENSIONS	Allowed file extensions. `"*"` matches any extension, `""` matches empty extension. Empty list excludes all files Ex: `[".py", ""]`	`[".js", ".vue"]`
JAVASCRIPT_ES_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"]`	Include every file
JAVASCRIPT_ES_PRE_COMMANDS	List of bash commands to run before the linter	None
JAVASCRIPT_ES_POST_COMMANDS	List of bash commands to run after the linter	None
JAVASCRIPT_ES_UNSECURED_ENV_VARIABLES	List of env variables explicitly not filtered before calling JAVASCRIPT_ES and its pre/post commands	None
JAVASCRIPT_ES_CONFIG_FILE	eslint configuration file nameUse `LINTER_DEFAULT` to let the linter find it	`.eslintrc.json`
JAVASCRIPT_ES_RULES_PATH	Path where to find linter configuration file	Workspace folder, then MegaLinter default rules
JAVASCRIPT_ES_DISABLE_ERRORS	Run linter but consider errors as warnings	`false`
JAVASCRIPT_ES_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	`0`
JAVASCRIPT_ES_CLI_EXECUTABLE	Override CLI executable	`['eslint']`

IDE Integration

Use eslint in your favorite IDE to catch errors before MegaLinter !

IDE	Extension Name	Install
Atom	linter-eslint	Visit Web Site
Brackets	brackets-eslint	Visit Web Site
Eclipse	Tern-Linter-ESLint	Visit Web Site
Emacs	flycheck	Visit Web Site
IDEA	ESLint Plugin
Sublime Text	SublimeLinter-eslint	Visit Web Site
vim	ale	Visit Web Site
vim	Syntastic	Visit Web Site
Visual Studio Code	vscode-eslint

MegaLinter Flavours

This linter is available in the following flavours

Flavor	Description	Embedded linters
all	Default MegaLinter Flavor	113
cupcake	MegaLinter for the most commonly used languages	81
javascript	Optimized for JAVASCRIPT or TYPESCRIPT based projects	56

Behind the scenes

How are identified applicable files

Activated only if one of these files is found: .eslintrc.json, .eslintrc.yml, .eslintrc.yaml, .eslintrc.js, .eslintrc.cjs, package.json:eslintConfig
File extensions: .js, .vue

How the linting is performed

eslint is called once with the list of files as arguments (list_of_files CLI lint mode)

Example calls

eslint myfile.js

eslint -c .eslintrc.json --no-eslintrc --no-ignore myfile.js

eslint --fix -c .eslintrc.json --no-eslintrc --no-ignore myfile.js

Help content

eslint [options] file.js [file.js] [dir]

Basic configuration:
  --no-eslintrc                   Disable use of configuration from .eslintrc.*
  -c, --config path::String       Use this configuration, overriding .eslintrc.* config options if present
  --env [String]                  Specify environments
  --ext [String]                  Specify JavaScript file extensions
  --global [String]               Define global variables
  --parser String                 Specify the parser to be used
  --parser-options Object         Specify parser options
  --resolve-plugins-relative-to path::String  A folder where plugins should be resolved from, CWD by default

Specify Rules and Plugins:
  --plugin [String]               Specify plugins
  --rule Object                   Specify rules
  --rulesdir [path::String]       Load additional rules from this directory. Deprecated: Use rules from plugins

Fix Problems:
  --fix                           Automatically fix problems
  --fix-dry-run                   Automatically fix problems without saving the changes to the file system
  --fix-type Array                Specify the types of fixes to apply (directive, problem, suggestion, layout)

Ignore Files:
  --ignore-path path::String      Specify path of ignore file
  --no-ignore                     Disable use of ignore files and patterns
  --ignore-pattern [String]       Pattern of files to ignore (in addition to those in .eslintignore)

Use stdin:
  --stdin                         Lint code provided on <STDIN> - default: false
  --stdin-filename String         Specify filename to process STDIN as

Handle Warnings:
  --quiet                         Report errors only - default: false
  --max-warnings Int              Number of warnings to trigger nonzero exit code - default: -1

Output:
  -o, --output-file path::String  Specify file to write report to
  -f, --format String             Use a specific output format - default: stylish
  --color, --no-color             Force enabling/disabling of color

Inline configuration comments:
  --no-inline-config              Prevent comments from changing config or rules
  --report-unused-disable-directives  Adds reported errors for unused eslint-disable directives

Caching:
  --cache                         Only check changed files - default: false
  --cache-file path::String       Path to the cache file. Deprecated: use --cache-location - default: .eslintcache
  --cache-location path::String   Path to the cache file or directory
  --cache-strategy String         Strategy to use for detecting changed files in the cache - either: metadata or content - default: metadata

Miscellaneous:
  --init                          Run config initialization wizard - default: false
  --env-info                      Output execution environment information - default: false
  --no-error-on-unmatched-pattern  Prevent errors when pattern is unmatched
  --exit-on-fatal-error           Exit with exit code 2 in case of fatal error - default: false
  --debug                         Output debugging information
  -h, --help                      Show help
  -v, --version                   Output the version number
  --print-config path::String     Print the configuration for the given file

Installation on mega-linter Docker image

NPM packages (node.js):