Weighted Damerau-Levenshtein Distance for Node.js

Weighted Damerau-Levenshtein and Levenshtein edit distance with configurable operation costs. Useful for typo tolerance, fuzzy matching, search ranking, and query correction in TypeScript/JavaScript/Node.js.

Install

npm install weighted-damerau-levenshtein

Requires Node.js 20 or newer.

Why this package

• Configurable insertion, deletion, and substitution weights
• Optional transposition support (useDamerau: true/false)
• Runtime input validation for safer production usage
• Zero runtime dependencies
• Included TypeScript declarations (index.d.ts)

Usage

const distance = require('weighted-damerau-levenshtein');

// Weighted Damerau-Levenshtein
const a = distance('hello word', 'Hello World!');
// 4 (two substitutions + two insertions)

// Lower insertion cost
const b = distance('hello word', 'Hello World!', { insWeight: 0.5 });
// 3

// Classic Levenshtein (Damerau disabled)
const c = distance('Hi there', 'Hi tehre', { useDamerau: false });
// 2

TypeScript

This package ships with built-in type declarations (index.d.ts).

import distance = require('weighted-damerau-levenshtein');

const score: number = distance('kitten', 'sitting', {
  insWeight: 1,
  delWeight: 1,
  subWeight: 1,
  useDamerau: true,
});

API

distance(source, target, options?) => number

Options:

• insWeight (number, default 1)
• delWeight (number, default 1)
• subWeight (number, default 1)
• useDamerau (boolean, default true)

Validation behavior:

• source and target must be strings
• Weights must be finite numbers greater than or equal to 0
• useDamerau must be a boolean
• Unknown option keys throw a TypeError

Development

npm install
npm run ci
npm run pack:check

npm run verify runs lint + tests on any supported Node version.
npm run test:coverage enforces strict 100% coverage thresholds (used in CI on Node 22).

Release

• CI runs in GitHub Actions from .github/workflows/ci.yml
• CI matrix runs verify on Node 20/22/24, with Node 25 as a non-blocking smoke check
• Strict 100% coverage enforcement runs on Node 22 and 24
• Publishing runs from .github/workflows/publish.yml on semver tags (vX.Y.Z)
• npm publish --provenance requires repository NPM_TOKEN and npm publisher setup

License

Licensed under Apache 2.0. See LICENSE.