Properties file reader for Node.js

Usage no npm install needed!

<script type="module">
  import propertiesReader from '';



An ini file compatible properties reader for Node.JS


The easiest installation is through NPM:

npm install properties-reader


Read properties from a file:

var propertiesReader = require('properties-reader');
var properties = propertiesReader('/path/to/properties.file');

The properties are then accessible either by fully qualified name, or if the property names are in dot-delimited notation, they can be access as an object:

// fully qualified name
var property = properties.get('');

// by object path
var property = properties.path();

To read more than one file, chain calls to the .append() method:


To read properties from a string, use the .read() method:' = Value \n = Another Value');

To set a single property into the properties object, use .set():

properties.set('', 'Property Value');

When reading a .ini file, sections are created by having a line that contains just a section name in square brackets. The section name is then prefixed to all property names that follow it until another section name is found to replace the current section.

# contents of properties file
some.thing = foo

some.thing = bar

// reading these back from the properties reader
properties.get('main.some.thing') == 'foo';
properties.get('blah.some.thing') == 'bar';

// looping through the properties reader
properties.each((key, value) => {
  // called for each item in the reader,
  // first with key=main.some.thing, value=foo
  // next with key=blah.some.thing, value=bar

// get all properties at once
  'main.some.thing': 'foo',
  'blah.some.thing': 'bar',

Checking for the current number of properties that have been read into the reader:

var propertiesCount = properties.length;

The length is calculated on request, so if accessing this in a loop an efficiency would be achieved by caching the value.

When duplicate names are found in the properties, the first one read will be replaced with the later one.

To get the complete set of properties, either loop through them with the .each((key, value) => {}) iterator or use the convenience method getAllProperties to return the complete set of flattened properties.

Saving changes

Once a file has been read and changes made, saving those changes to another file is as simple as running:

// async/await ES6
const propertiesReader = require('properties-reader');
const props = propertiesReader(filePath, {writer: { saveSections: true }});

// ES5 callback styles, function then(err, data) { ... });

// ES5 promise style, onSaveError);

To output the properties without any section headings, set the saveSections option to false

Data Types

Properties will automatically be converted to their regular data types when they represent true/false or numeric values. To get the original value without any parsing / type coercion applied, use properties.getRaw('').

FAQ / Breaking Changes

Duplicate Section Headings

From version 2.0.0 the default behaviour relating to multiple [section] blocks with the same name has changed so combine the items of each same-named section into the one section. This is only visible when saving the items (via

To restore the previous behaviour which would allow duplicate [...] blocks to be created, supply an appender configuration with the property allowDuplicateSections set to true.

const propertiesReader = require('properties-reader');
const props = propertiesReader(filePath, 'utf-8', { allowDuplicateSections: true });


If you find bugs or want to change functionality, feel free to fork and pull request.