porter2  

Very fast JavaScript implementation of the porter2 English stemming algorithm.

$ npm install porter2

Usage

The package is simple: it has no dependencies and exports a single function named stem.

Import using CommonJS:

const { stem } = require('porter2')

Or, import using EcmaScript Modules (through interoperability with CommonJS):

import { stem } from 'porter2'

Use the stemmer:

const word = stem('animadversion')
console.log(word) //=> animadvers

This stemmer expects a lowercase English word.

TypeScript type declarations are included.

Benchmarks

Here is a comparison with some other libraries benchmarked over the 29.4k test suite in a hot loop (you probably should take it with a little grain of salt):

| library | throughput (node) | throughput (bun) | slower | | ------------------------------------ | ----------------- | ---------------- | ------- | | porter2 2.0.0 | 11157 kops/s | 11092 kops/s | 1.000× | | stemr 1.0.0 | 958 kops/s | 1194 kops/s | 11.641× | | wink-porter2-stemmer [^1] 2.0.1 | 325 kops/s | 407 kops/s | 34.319× |

Here are libraries that implement the older porter version 1 (note the behavior is not identical):

| library | throughput (node) | throughput (bun) | slower | | ------------------------------------ | ----------------- | ---------------- | ------- | | porter-stemmer-js [^2] 1.1.2 | 3081 kops/s | 3583 kops/s | 3.621× | | stemmer [^3] 2.0.1 | 2030 kops/s | 1789 kops/s | 5.496× | | @stdlib/nlp-porter-stemmer 0.2.3 | 1588 kops/s | 1523 kops/s | 7.024× | | porter-stemmer 0.9.1 | 902 kops/s | 1245 kops/s | 12.373× |

The benchmark code is in bench/run.mjs (bench/all.mjs for all libraries). This was tested with Node.js v24.15.0 and bun v1.3.13 on Zen 3 (4.5 GHz boosted).

[^1]: wink-porter2-stemmer is 99.97% porter2 compliant (fails on ' cases only)

[^2]: That one has similar goals and, surprisingly, was published just 3 days before this package! (And after the author started working on porter2.js.)

[^3]: ESM only