Snowball Stemmers

0.6.0 verified Sat Apr 25 auth: no javascript

JavaScript port of the Snowball stemming algorithms (http://snowball.tartarus.org/), supporting 24 languages including Arabic, Russian, English, and more. The current stable version is 0.6.0, released sporadically. It is autogenerated from the Snowball compiler and uses ESJava. Key differentiators: lightweight, no dependencies, pure JS, and supports a wide range of languages. Compared to alternatives like natural or stemming libraries, it focuses on comprehensive language coverage. The library provides a simple factory API for creating stemmers and lists available algorithms.

Common errors

error TypeError: require(...).newStemmer is not a function ↓

cause Incorrect import style using named import or requiring wrong path.

fix

Use const snowballFactory = require('snowball-stemmers'); then snowballFactory.newStemmer('english').

error Error: algorithm 'russin' not supported ↓

cause Misspelling the language name.

fix

Check available algorithms with snowballFactory.algorithms(). Use exact string like 'russian'.

error TypeError: stemmer.stem is not a function ↓

cause Accessing stem method on the factory instead of an instance.

fix

Create a stemmer instance first: const stemmer = snowballFactory.newStemmer('english'); then call stemmer.stem(word).

Warnings

gotcha The stem method may not handle non-ASCII characters correctly in all languages (e.g., Unicode normalization). ↓

fix Normalize input strings (NFKC) before stemming.

gotcha The package uses CommonJS and cannot be imported with ES module import syntax directly. ↓

fix Use require() instead of import. If using ESM, create a dynamic import wrapper.

deprecated Some algorithms like 'porter' are legacy and may be superseded by more recent Snowball algorithms. ↓

fix Use language-specific algorithm (e.g., 'english') instead of 'porter'.

gotcha The package is unmaintained since 2018; no updates for new languages or bug fixes. ↓

fix Consider using 'snowball-stemmer' (fork) or 'natural' library for active maintenance.

Install

npm install snowball-stemmers

yarn add snowball-stemmers

pnpm add snowball-stemmers

Imports

newStemmer (via default export)

wrong

import { newStemmer } from 'snowball-stemmers'; // wrong: not a named export

correct

const snowballFactory = require('snowball-stemmers'); const stemmer = snowballFactory.newStemmer('english');

The package does not ship ES module types; it exports a factory function as default. Use CommonJS require. No type definitions provided.

algorithms

wrong

const algorithms = require('snowball-stemmers/algorithms'); // wrong: no submodule path

correct

const snowballFactory = require('snowball-stemmers'); const algs = snowballFactory.algorithms();

algorithms is a method on the default export, listing all supported language names.

Stemmer instance (prototype methods)

wrong

const result = snowballFactory.stem('чаво', 'russian'); // wrong: no such static method

correct

const stemmer = snowballFactory.newStemmer('russian'); const result = stemmer.stem('чаво');

Each stemmer instance has a stem() method. The factory creates instances per language.

Quickstart

Shows how to require the factory, create a stemmer for English, stem a word, and list all available algorithms.

const snowballFactory = require('snowball-stemmers');

const stemmer = snowballFactory.newStemmer('english');
console.log(stemmer.stem('running')); // 'run'

console.log(snowballFactory.algorithms());
// ['arabic', 'armenian', ..., 'turkish']