js-java-properties

A JavaScript/TypeScript library for parsing, modifying, and stringifying Java .properties files while preserving formatting and comments. Version 1.1.0 (stable, released 2024) uses an array-of-lines backing store to allow in-place editing without reformatting, unlike typical parsers that convert to plain objects. Supports ESM and CommonJS, ships TypeScript types, and requires Node >= 20. Provides functions: parse, stringify, listProperties, getProperty, setProperty, toObject, toMap, empty. Handles duplicate keys, comments, multi-line values, and separator styles (':', '=', or space).