Prettier 30 🎨 Cheatsheet

Prettier 3.x is ESM-first, async, and plugin-driven. The config file resolution searches upward from the file being formatted, and the first config found wins. The CLI flags map to the API options, and the plugins are the extension surface for languages and sorting.

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The CLI Commands

Command	Purpose
prettier .	Format to stdout (no write)
prettier . --write	Format in place
prettier . --check	Check formatting, exit 1 if unformatted
prettier . --list-different	List unformatted files
prettier . --debug-check	Verify correctness preservation
prettier . --find-config-path <file>	Locate the config for a file

The --check and --list-different flags are the CI gates. The --write flag is the local correction step.

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The Core Options

Option	Default	CLI
printWidth	80	--print-width <int>
tabWidth	2	--tab-width <int>
useTabs	false	--use-tabs
semi	true	--no-semi
singleQuote	false	--single-quote
quoteProps	"as-needed"	--quote-props <as-needed|consistent|preserve>
jsxSingleQuote	false	--jsx-single-quote
trailingComma	"all"	--trailing-comma <all|es5|none>
bracketSpacing	true	--no-bracket-spacing
arrowParens	"always"	--arrow-parens <always|avoid>
endOfLine	"lf"	--end-of-line <lf|crlf|cr|auto>

The trailingComma default changed to "all" in 3.0. The arrowParens default is "always".

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The Parser Option

Prettier infers the parser from the file extension. The --parser flag overrides the inference for stdin or unknown extensions.

Parser	Language
babel	JavaScript (default)
babel-ts	TypeScript via Babel
typescript	TypeScript
flow	Flow
espree	JavaScript (ESLint parser)
css / scss / less	Stylesheets
json / json5 / jsonc	JSON variants
markdown / mdx	Markdown
html / vue / angular	HTML variants
yaml	YAML
graphql	GraphQL

The --stdin-filepath flag infers the parser from a filename when reading from stdin.

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The Config File Resolution

The config is resolved from the file being formatted, searching upward. The first config found wins. The supported forms, in order of precedence:

1. "prettier" key in package.json
2. .prettierrc (JSON or YAML)
3. .prettierrc.json, .prettierrc.yml, .prettierrc.yaml, .prettierrc.json5
4. .prettierrc.js, prettier.config.js, .prettierrc.ts, prettier.config.ts (ESM or CJS)
5. .prettierrc.mjs, prettier.config.mjs, .prettierrc.mts, prettier.config.mts
6. .prettierrc.cjs, prettier.config.cjs, .prettierrc.cts, prettier.config.cts
7. .prettierrc.toml

The --config <path> flag bypasses the search and points to a specific file.

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The Overrides Pattern

The overrides array applies options to matching files. The files pattern is relative to the config file’s directory, not the cwd.

{
  "semi": false,
  "overrides": [
    { "files": "*.test.js", "options": { "semi": true } },
    { "files": ["*.html", "legacy/**/*.js"], "options": { "tabWidth": 4 } }
  ]
}

A pattern without a / matches the filename alone at any depth. The excludeFiles property excludes files from an override.

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The Ignore Mechanism

Prettier 3.x honors .gitignore by default. The .prettierignore file adds project-specific exclusions.

Mechanism	Scope
.gitignore	Honored by default in 3.x
.prettierignore	Project-specific exclusions
--ignore-path <path>	Custom ignore file
// prettier-ignore	Next AST node in a file

The --ignore-path flag accepts multiple files. The .prettierignore uses gitignore syntax.

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The Shared Config Pattern

A shareable config is a module that exports a config object. The consuming package references it by name.

// package.json
{ "prettier": "@company/prettier-config" }

The package.json reference does not support extending. A package that needs overrides imports the config and spreads it.

// prettier.config.mjs
import sharedConfig from "@company/prettier-config";
export default { ...sharedConfig, printWidth: 100 };

The spread is shallow. A package that changes the plugins array must spread the shared array and append the new plugin.

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The Plugin Surface

A Prettier 3 plugin exports languages, parsers, and printers.

Export	Purpose
languages	File extensions and parser names
parsers	parse, locStart, locEnd
printers	print (returns a Doc), comment hooks, insertPragma

The print function returns a Doc, not a string. The Doc is built with prettier.doc.builders (group, line, indent, concat). Async parsers are supported. The custom parser API was removed in 3.0.

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The Common Plugins

Plugin	Purpose
prettier-plugin-tailwindcss	Sort Tailwind classes
@ianvs/prettier-plugin-sort-imports	Sort imports (safer fork)
@trivago/prettier-plugin-sort-imports	Sort imports (original)
prettier-plugin-organize-imports	Sort and remove unused (broken with TS 7)

The Tailwind plugin needs tailwindStylesheet (v4) or tailwindConfig (v3). The import-sorting plugins use importOrder with special words (<BUILTIN_MODULES>, <THIRD_PARTY_MODULES>, <TYPES>).

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The 3.0 Breaking Changes

Change	Detail
ESM source	CJS bridge still works for library use
format() async	Returns Promise<string>
Custom parser removed	Plugin API is the replacement
trailingComma default	"all" (was "es5")
Flow in babel parser	Removed; use flow parser or @flow pragma
Markdown CJK spacing	No space between CJK and Latin

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The API Calls

Function	Returns	Notes
prettier.format(source, options)	Promise<string>	Async in 3.x
prettier.check(source, options)	Promise<boolean>	Async in 3.x
prettier.resolveConfig(filePath)	Promise<object | null>	Searches upward
prettier.getFileInfo(filePath)	Promise<{ ignored, inferredParser }>	The formattable gate

The format and check functions require await. The resolveConfig result is spread into the options. The filepath option infers the parser.

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The One-Line Summary

ESM source. Async API. Plugin-driven. Config searches upward. trailingComma is "all".

Prettier 3.x is a formatter that migrated to ESM, removed the synchronous API, and replaced the custom parser with the plugin contract. The config is resolved from the file being formatted, and the first config found wins. The plugins are the language and sorting extensions. The CLI is the gate, and the API is the integration.

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Summary

Area	Key takeaway
CLI	--write, --check, --list-different
Options	trailingComma: "all", printWidth: 80, semi: true
Parser	Inferred from extension; --parser overrides
Config	Searches upward; first found wins
Overrides	files relative to config file
Ignore	.gitignore honored; .prettierignore adds
Shared config	Module export, reference by name
Plugins	languages, parsers, printers
3.0 changes	ESM, async, custom parser removed

Remember: Prettier 3.x is ESM-first and async. The config searches upward, and the first config found wins. The trailingComma default is "all". The plugins are the language and sorting extensions, and the print function returns a Doc. The CLI is the gate, and the API is the integration. The custom parser is gone; the plugin is the replacement.

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