Registry / devops / js-java-properties

js-java-properties

library1.1.0jsnpmunverified

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).

devops

npm install js-java-properties

github ↗package ↗homepage ↗

INSTALL

IMPORT

SIG · JS-JAVA-PROPERTIES

js-java-properties

devopsjavascriptv1.1.0

harness data pending

Install & Compatibility

Where this runs

No compatibility data collected yet for this library.

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

parse

✓ import { parse } from 'js-java-properties'

✗ const { parse } = require('js-java-properties')

ESM import is preferred. CommonJS require works in Node >= 20.

stringify

✓ import { stringify } from 'js-java-properties'

✗ import * as props from 'js-java-properties'; props.stringify(propsObj)

stringify is a named export; importing as namespace and calling .stringify is also correct.

Properties (type)

✓ import type { Properties } from 'js-java-properties'

✗ import { Properties } from 'js-java-properties'

Properties is a type/interface, not a runtime value. Use type import for proper TypeScript.

KeyValuePair (type)

✓ import type { KeyValuePair } from 'js-java-properties'

✗ import { KeyValuePair } from 'js-java-properties'

KeyValuePair is a type, not a constructor. Must use type import.

listProperties

✓ import { listProperties } from 'js-java-properties'

✗ import * as props from 'js-java-properties'; props.listProperties(props)

listProperties is a named export. Accepts Properties object and returns iterable of KeyValuePair.

Demonstrates parsing, getting/setting properties, converting to object, listing key-value pairs, creating empty properties and stringifying.

import { parse, empty, stringify, getProperty, setProperty, toObject, listProperties } from 'js-java-properties'; // Parse a properties string const props = parse('key1=value1\nkey2 = value2\n# comment\nkey3: value3'); console.log(props); // { lines: [ 'key1=value1', 'key2 = value2', '# comment', 'key3: value3' ] } // Get a property (case-sensitive) console.log(getProperty(props, 'key2')); // 'value2' // Set a property (adds or updates) setProperty(props, 'key2', 'new-value'); console.log(props.lines); // includes 'key2 = new-value' // Convert to object const obj = toObject(props); console.log(obj); // { key1: 'value1', key2: 'new-value', key3: 'value3' } // List all key-value pairs (including duplicates) for (const { key, value } of listProperties(props)) { console.log(`${key}=${value}`); } // Create empty properties and add lines const emptyProps = empty(); emptyProps.lines.push('newKey=new value'); const output = stringify(emptyProps); console.log(output); // 'newKey=new value\n' // Read from file (Node.js) import fs from 'node:fs'; const fileContent = fs.readFileSync('config.properties', 'utf-8'); const fileProps = parse(fileContent);

Debug

Known issues

gotchagetProperty() returns the last occurrence of a duplicate key, not the first.

fix

If you need first occurrence, use listProperties() and stop on first match.

affects: >=0.0.0

gotchasetProperty() modifies the object in place and returns void. It does not return a new object.

fix

Be careful not to expect a return value; check the updated props object directly.

affects: >=0.0.0

gotchasetProperty() with value undefined removes the key entirely. If you want to set empty string, pass empty string explicitly.

fix

Use setProperty(props, 'key', undefined) to remove; use setProperty(props, 'key', '') to set empty.

affects: >=0.0.0

gotchaProperties object is mutable; your code may unintentionally modify the internal lines array.

fix

Clone the lines array if you need to preserve original: props.lines = [...props.lines];

affects: >=0.0.0

breakingVersion 1.0.0 dropped support for Node < 20.

fix

Upgrade Node.js to version 20 or later.

affects: >=1.0.0

deprecatedNo functions are currently deprecated, but the Properties type may be extended in future minor versions.

fix

Prepare for possible additions by not assuming a fixed shape beyond 'lines'.

affects: >=1.0.0

gotchaMulti-line property values (backslash continuation) are not expanded into single lines in the lines array; each line is stored separately.

fix

Use listProperties() or toObject() to get the combined value.

affects: >=0.0.0

Errors

Common errors & fixes

TypeError: (0 , properties.parse) is not a function

Trying to call parse as a default export after a namespace import.

fix

Use named import: import { parse } from 'js-java-properties';

Module not found: Error: Can't resolve 'js-java-properties'

Missing install or incorrect import path. Package is ESM/CJS compatible.

fix

Run npm install js-java-properties or check that package.json includes it.

Cannot find name 'Properties'.

Trying to use Properties type without importing it as a type.

fix

Use import type { Properties } from 'js-java-properties';

Property 'lines' does not exist on type 'void'.

Calling setProperty() and trying to access .lines on its return value (which is void).

fix

setProperty modifies the object in place; access .lines on the original props object.

Uncaught SyntaxError: The requested module 'js-java-properties' does not provide an export named 'default'

Trying to import default from a package that only has named exports.

fix

Use named imports: import { parse, empty, stringify } from 'js-java-properties';

Upgrade

Version history

1.1.0latest on npm

Audit

Dependencies

No dependency data recorded yet.

Agent activity

7 hits · last 30 days

node

Resources

githubhttps://github.com/mdvorak/js-java-properties ↗

packagejs-java-properties ↗

homepagehttps://github.com/mdvorak/js-java-properties#readme ↗