Prettier Plugin for Properties Files

0.3.1 verified Sat Apr 25 auth: no javascript

A Prettier plugin that adds support for formatting .properties files, version 0.3.1, with a stable release cadence and active maintenance. It integrates with Prettier v2.3 and later, providing dedicated formatting for Java-style property files. Key differentiators include support for escape non-Latin-1 characters (for ISO-8859-1 encoding) and customizable key-value separators (space, colon, equals with various spacing). Unlike generic formatters, this plugin understands the .properties syntax, handling comments, multi-line values, and Unicode escaping correctly.

Common errors

error Cannot find module 'prettier-plugin-properties' ↓

cause Plugin not installed or not in node_modules.

fix

Run npm install --save-dev prettier-plugin-properties

error Configuration file contains a plugin that is not installed: prettier-plugin-properties ↓

cause Plugin listed in .prettierrc but missing from node_modules.

fix

Install the plugin or remove it from the plugins array.

error TypeError: Cannot read properties of undefined (reading 'properties') ↓

cause The plugin expects a valid .properties file but the file is empty or malformed.

fix

Ensure the file has at least one key-value pair or comment.

Warnings

breaking Prettier v3 no longer autoloads plugins. You must explicitly list plugins in config. ↓

fix Add 'prettier-plugin-properties' to the plugins array in .prettierrc or use --plugins in CLI.

gotcha Plugin only works with Prettier >= 2.3.0 and Node.js >= 18 (v0.3.0+). ↓

fix Upgrade Prettier to 2.3+ and Node to 18+.

deprecated v0.2.0 dropped runtime dependency on linguist-languages, but configuration remains the same. ↓

fix No action needed; upgrade to v0.2.0 or later.

gotcha Features like escapeNonLatin1 only affect non-Latin-1 characters; Latin-1 characters (e.g., ñ) are left as-is. ↓

fix Use escapeNonLatin1: true to force escape of all non-Latin-1 characters.

Install

npm install prettier-plugin-properties

yarn add prettier-plugin-properties

pnpm add prettier-plugin-properties

Imports

plugin
wrong
```
import plugin from 'prettier-plugin-properties'
```
correct
```
// In .prettierrc: plugins: ['prettier-plugin-properties']
```
This is a Prettier plugin, not a library with programmatic exports. It is configured via Prettier's plugins array.
escapeNonLatin1
wrong
```
import { escapeNonLatin1 } from 'prettier-plugin-properties'
```
correct
```
// In .prettierrc: { escapeNonLatin1: true }
```
escapeNonLatin1 is an option passed to Prettier, not a named export from this package.
keySeparator
wrong
```
const { keySeparator } = require('prettier-plugin-properties')
```
correct
```
// In .prettierrc: { keySeparator: ' = ' }
```
keySeparator is a Prettier option, not a package export. Must be set in Prettier config.

Quickstart

Shows installation, configuration with options, and formatting of a .properties file.

// Install
npm install --save-dev prettier prettier-plugin-properties

// .prettierrc
{
  "plugins": ["prettier-plugin-properties"],
  "keySeparator": " = ",
  "escapeNonLatin1": false
}

// Run
npx prettier --write file.properties

// file.properties input
name = John Doe
age=30
key with spaces: value
\u00e9\u00e0

// file.properties output
name = John Doe
age = 30
key with spaces = value
\u00e9\u00e0