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2.2.2 • Public • Published


Build, generate, parse, and evaluate LDAP filters

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A library for working with Lightweight Directory Access Protocol (LDAP) filters based on RFC 4515.

Although this format is typicaly used with the LDAP protocol, this library could be implemented in other applications that need portable string-based filters for the purpose of matching object data.



Use npm:

npm install ldap-filters

Build a filter (programatically)

var Filter = require('ldap-filters');
var output = Filter.AND([

Note: You must call the .toString() method, to obtain the filter as a string.

Matching methods

Various methods can be used to build simple filters:

  • .present() - tests for presence (attr=*)
  • .equalTo(value) - tests for equality (attr=value)
  • .contains(value) - tests if attribute contains value (attr=*value*)
  • .endsWith(value) - tests if attribute ends with value (attr=*value)
  • .startsWith(value) - tests if attribute starts with value (attr=value*)
  • .approx(value) - tests if value is approximate match (attr~=value)
  • .gte(value) - tests if value is greater than or equal (attr>=value)
  • .lte(value) - tests if value is less than or equal (attr<=value)
  • .raw(value) - add an raw (escaped) attribute value (attr=value)

Added in 2.x The .raw method is useful for building filters that have complex substring matches not suitable for .startsWith(), .endsWith(), or .contains() — however, you will need to escape any values that require escaping. This can be done using Filter.escape() like so:

var match_value = '*' + Filter.escape('James (Jimmy)') + '*';
var filter = Filter.attribute('cn').raw(match_value);
match_value == '*James \\28Jimmy\\29*' // true

Logical/Aggregate methods

Simple filters can be aggregated with AND, OR, and NOT:

  • Filter.AND(list) - AND a list (array) of filters (&(f1)(f2)..)
  • Filter.OR(list) - OR a list (array) of filters (|(f1)(f2)..)
  • Filter.NOT(filter) - NOT (negate) a filter (!(filter))

Aggregation and nesting can be used to build complex filters.

Parse a filter

Parses a filter from a string, returning a Filter object.

var Filter = require('ldap-filters');
var input = '(&(givenName=jenny)(sn=jensen))';

Simplify a filter

The .simplify() method will reduce any AND or OR filters that have only one child/condition and replace them with that filter. NOT filters, and any other filters will remain intact.

var input = '(&(uid=jenny))';
Filter.parse(input).simplify().toString() // => '(uid=jenny)'


Whether you've created a filter programatically or by parsing a filter, you can output with toString() method or by concatenating with a string, like so:

filter + ''

This will result in compacted output with no whitespace like:


If you pass a value of true or a numeric indentation value to toString(), the output will be beautified with space indentation.


Will result in similar output to the following:


A value of true will use Filter.indent property, which defaults to 4. The indentation character defaults to a space, see Filter.indent_char

Evaluate data against a filter

Test if (object) data matches a given filter. The filter can be one created programatically, or parsed from a text string. A boolean true value will be returned for a successful match.

var Filter = require('ldap-filters');
var input = '(&(givenName~=jeni)(sn=jensen))';
var parsed = Filter.parse(input);
var data = { givenName: 'Jenny', sn: 'Jensen' };

Unit Tests

A complete test suite is included. To run it, you will need to have mocha and chai installed. Mocha should be installed globally (need sudo?).

npm install -g mocha
npm install chai

Tests can be run from npm or manually with mocha:

# Run tests with npm 
npm test
# Run tests manually 
mocha test/*.js


The parser is built with pegjs. To re-build the parser, you'll need the pegjs dev dependency installed.

# Build parser with npm 
npm run build
# Build manually with pegjs 
# requires pegjs command to be availble (npm i -g pegjs) 
pegjs lib/parser.pegjs lib/parser.js


Version 1.x and lower used jison parser source originally written by tantaman found in the DATS-DAP repository.

Version 2.x and above are using an updated original pegjs-based parser. This version offers better RFC-compliance and improved matching for complicated substring matches and escaped characters, as well as addressing some bugs found in the previous jison parser.

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