prettier

Prettier is the industry-standard opinionated code formatter with excellent JSON support that automatically formats JSON files for consistency and readability. It brings professional formatting standards to JSON data across configuration files, APIs, and data structures.

Key Features:

JSON-Specific Formatting: Specialized handling of JSON syntax with proper indentation, spacing, and structure
Consistent Output: Deterministic formatting ensures identical results across different environments and developers
Parse Safety: AST-based processing validates JSON syntax while formatting, catching errors during formatting
Opinionated Approach: Zero-configuration setup with sensible defaults optimized for JSON readability
Fast Performance: High-speed formatting suitable for large JSON files
Nested Structure Handling: Intelligent formatting of complex nested objects and arrays for optimal readability
Team Standardization: Eliminates JSON formatting debates and ensures uniform data structure presentation
Configuration Flexibility: Supports project-specific formatting rules through .prettierrc when customization is needed

prettier documentation

Version in MegaLinter: 3.6.2
Visit Official Web Site
See How to configure prettier rules
See How to disable prettier rules in files
See Index of problems detected by prettier

Configuration in MegaLinter

Enable prettier by adding JSON_PRETTIER in ENABLE_LINTERS variable
Disable prettier by adding JSON_PRETTIER in DISABLE_LINTERS variable

Enable autofixes by adding JSON_PRETTIER in APPLY_FIXES variable

Variable	Description	Default value
JSON_PRETTIER_ARGUMENTS	User custom arguments to add in linter CLI call Ex: `-s --foo "bar"`
JSON_PRETTIER_COMMAND_REMOVE_ARGUMENTS	User custom arguments to remove from command line before calling the linter Ex: `-s --foo "bar"`
JSON_PRETTIER_FILTER_REGEX_INCLUDE	Custom regex including filter Ex: `(src\\|lib)`	Include every file
JSON_PRETTIER_FILTER_REGEX_EXCLUDE	Custom regex excluding filter Ex: `(test\\|examples)`	Exclude no file
JSON_PRETTIER_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`
JSON_PRETTIER_FILE_EXTENSIONS	Allowed file extensions. `"*"` matches any extension, `""` matches empty extension. Empty list excludes all files Ex: `[".py", ""]`	`[".json"]`
JSON_PRETTIER_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
JSON_PRETTIER_PRE_COMMANDS	List of bash commands to run before the linter	None
JSON_PRETTIER_POST_COMMANDS	List of bash commands to run after the linter	None
JSON_PRETTIER_UNSECURED_ENV_VARIABLES	List of env variables explicitly not filtered before calling JSON_PRETTIER and its pre/post commands	None
JSON_PRETTIER_CONFIG_FILE	prettier configuration file nameUse `LINTER_DEFAULT` to let the linter find it	`.prettierrc.json`
JSON_PRETTIER_RULES_PATH	Path where to find linter configuration file	Workspace folder, then MegaLinter default rules
JSON_PRETTIER_DISABLE_ERRORS	Run linter but consider errors as warnings	`true`
JSON_PRETTIER_DISABLE_ERRORS_IF_LESS_THAN	Maximum number of errors allowed	`0`
JSON_PRETTIER_CLI_EXECUTABLE	Override CLI executable	`['prettier']`

IDE Integration

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

IDE	Extension Name	Install
Emacs	prettier-emacs	Visit Web Site
Emacs	prettier.el	Visit Web Site
Emacs	apheleia	Visit Web Site
IDEA	Prettier
Sublime Text	JsPrettier	Visit Web Site
vim	vim-prettier	Visit Web Site
visual_studio	JavaScriptPrettier	Visit Web Site
Visual Studio Code	prettier-vscode

MegaLinter Flavors

This linter is available in the following flavors

Flavor	Description	Embedded linters
all	Default MegaLinter Flavor	126
c_cpp	Optimized for pure C/C++ projects	56
ci_light	Optimized for CI items (Dockerfile, Jenkinsfile, JSON/YAML schemas,XML	22
cupcake	MegaLinter for the most commonly used languages	87
documentation	MegaLinter for documentation projects	49
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
formatters	Contains only formatters	18
go	Optimized for GO based projects	51
java	Optimized for JAVA based projects	54
javascript	Optimized for JAVASCRIPT or TYPESCRIPT based projects	59
php	Optimized for PHP based projects	54
python	Optimized for PYTHON based projects	65
ruby	Optimized for RUBY based projects	50
rust	Optimized for RUST based projects	50
salesforce	Optimized for Salesforce based projects	54
swift	Optimized for SWIFT based projects	50
terraform	Optimized for TERRAFORM based projects	54

Behind the scenes

How are identified applicable files

File extensions: .json

How the linting is performed

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

Example calls

prettier --check myfile.json

prettier --config .prettierrc.json --check myfile.json

prettier --config .prettierrc.json --write myfile.json

Help content

Usage: prettier [options] [file/dir/glob ...]

By default, output is written to stdout.
Stdin is read if it is piped to Prettier and no files are given.

Output options:

  -c, --check              Check if the given files are formatted, print a human-friendly summary
                           message and paths to unformatted files (see also --list-different).
  -l, --list-different     Print the names of files that are different from Prettier's formatting (see also --check).
  -w, --write              Edit files in-place. (Beware!)

Format options:

  --arrow-parens <always|avoid>
                           Include parentheses around a sole arrow function parameter.
                           Defaults to always.
  --bracket-same-line      Put > of opening tags on the last line instead of on a new line.
                           Defaults to false.
  --no-bracket-spacing     Do not print spaces between brackets.
  --embedded-language-formatting <auto|off>
                           Control how Prettier formats quoted code embedded in the file.
                           Defaults to auto.
  --end-of-line <lf|crlf|cr|auto>
                           Which end of line characters to apply.
                           Defaults to lf.
  --experimental-operator-position <start|end>
                           Where to print operators when binary expressions wrap lines.
                           Defaults to end.
  --no-experimental-ternaries
                           Default behavior of ternaries; keep question marks on the same line as the consequent.
  --html-whitespace-sensitivity <css|strict|ignore>
                           How to handle whitespaces in HTML.
                           Defaults to css.
  --jsx-single-quote       Use single quotes in JSX.
                           Defaults to false.
  --object-wrap <preserve|collapse>
                           How to wrap object literals.
                           Defaults to preserve.
  --parser <flow|babel|babel-flow|babel-ts|typescript|acorn|espree|meriyah|css|less|scss|json|json5|jsonc|json-stringify|graphql|markdown|mdx|vue|yaml|glimmer|html|angular|lwc|mjml>
                           Which parser to use.
  --print-width <int>      The line length where Prettier will try wrap.
                           Defaults to 80.
  --prose-wrap <always|never|preserve>
                           How to wrap prose.
                           Defaults to preserve.
  --quote-props <as-needed|consistent|preserve>
                           Change when properties in objects are quoted.
                           Defaults to as-needed.
  --no-semi                Do not print semicolons, except at the beginning of lines which may need them.
  --single-attribute-per-line
                           Enforce single attribute per line in HTML, Vue and JSX.
                           Defaults to false.
  --single-quote           Use single quotes instead of double quotes.
                           Defaults to false.
  --tab-width <int>        Number of spaces per indentation level.
                           Defaults to 2.
  --trailing-comma <all|es5|none>
                           Print trailing commas wherever possible when multi-line.
                           Defaults to all.
  --use-tabs               Indent with tabs instead of spaces.
                           Defaults to false.
  --vue-indent-script-and-style
                           Indent script and style tags in Vue files.
                           Defaults to false.

Config options:

  --config <path>          Path to a Prettier configuration file (.prettierrc, package.json, prettier.config.js).
  --no-config              Do not look for a configuration file.
  --config-precedence <cli-override|file-override|prefer-file>
                           Define in which order config files and CLI options should be evaluated.
                           Defaults to cli-override.
  --no-editorconfig        Don't take .editorconfig into account when parsing configuration.
  --find-config-path <path>
                           Find and print the path to a configuration file for the given input file.
  --ignore-path <path>     Path to a file with patterns describing files to ignore.
                           Multiple values are accepted.
                           Defaults to [.gitignore, .prettierignore].
  --plugin <path>          Add a plugin. Multiple plugins can be passed as separate `--plugin`s.
                           Defaults to [].
  --with-node-modules      Process files inside 'node_modules' directory.

Editor options:

  --cursor-offset <int>    Print (to stderr) where a cursor at the given position would move to after formatting.
                           Defaults to -1.
  --range-end <int>        Format code ending at a given character offset (exclusive).
                           The range will extend forwards to the end of the selected statement.
                           Defaults to Infinity.
  --range-start <int>      Format code starting at a given character offset.
                           The range will extend backwards to the start of the first line containing the selected statement.
                           Defaults to 0.

Other options:

  --cache                  Only format changed files. Cannot use with --stdin-filepath.
                           Defaults to false.
  --cache-location <path>  Path to the cache file.
  --cache-strategy <metadata|content>
                           Strategy for the cache to use for detecting changed files.
  --check-ignore-pragma    Check whether the file's first docblock comment contains '@noprettier' or '@noformat' to determine if it should be formatted.
                           Defaults to false.
  --no-color               Do not colorize error messages.
  --no-error-on-unmatched-pattern
                           Prevent errors when pattern is unmatched.
  --file-info <path>       Extract the following info (as JSON) for a given file path. Reported fields:
                           * ignored (boolean) - true if file path is filtered by --ignore-path
                           * inferredParser (string | null) - name of parser inferred from file path
  -h, --help <flag>        Show CLI usage, or details about the given flag.
                           Example: --help write
  -u, --ignore-unknown     Ignore unknown files.
  --insert-pragma          Insert @format pragma into file's first docblock comment.
                           Defaults to false.
  --log-level <silent|error|warn|log|debug>
                           What level of logs to report.
                           Defaults to log.
  --require-pragma         Require either '@prettier' or '@format' to be present in the file's first docblock comment in order for it to be formatted.
                           Defaults to false.
  --stdin-filepath <path>  Path to the file to pretend that stdin comes from.
  --support-info           Print support information as JSON.
  -v, --version            Print Prettier version.

Installation on mega-linter Docker image

Dockerfile commands :

# renovate: datasource=npm depName=prettier
ARG NPM_PRETTIER_VERSION=3.6.2

NPM packages (node.js):
- prettier@3.6.2