Fuse.js fuzzy search with weighted keys and a prebuilt index: working versions (tested 2026-10-15)

{
  "name": "fuse-js-weighted-search",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node --import tsx --test test/*.test.ts"
  },
  "dependencies": {
    "fuse.js": "7.5.0"
  },
  "devDependencies": {
    "@types/node": "26.6.5",
    "tsx": "4.23.15"
  }
}

import Fuse, { type IFuseOptions } from "fuse.js";

export type Product = { id: string; title: string; brand: string; tags: string[] };

const options: IFuseOptions<Product> = {
  keys: [
    { name: "title", weight: 0.7 },
    { name: "brand", weight: 0.2 },
    { name: "tags", weight: 0.1 },
  ],
  includeScore: true,
  includeMatches: true,
  threshold: 0.4,
  ignoreLocation: true,
};

export function buildSearch(items: Product[]) {
  // Pre-built index so the same index can be cached or shipped to the client.
  const index = Fuse.createIndex(options.keys!, items);
  return new Fuse(items, options, index);
}

export function search(fuse: Fuse<Product>, q: string, limit = 5) {
  return fuse.search(q, { limit }).map((r) => ({ id: r.item.id, score: r.score!, keys: r.matches?.map((m) => m.key) ?? [] }));
}

export function serializeIndex(fuse: Fuse<Product>) {
  return JSON.stringify(fuse.getIndex().toJSON());
}

export function loadSearch(items: Product[], json: string) {
  return new Fuse(items, options, Fuse.parseIndex<Product>(JSON.parse(json)));
}

import { test } from "node:test";
import assert from "node:assert/strict";
import { buildSearch, search, serializeIndex, loadSearch, type Product } from "../src/search.ts";

const items: Product[] = [
  { id: "1", title: "Steel toe work boots", brand: "Carhartt", tags: ["safety", "footwear"] },
  { id: "2", title: "Hard hat with visor", brand: "MSA", tags: ["safety", "head"] },
  { id: "3", title: "Insulated gloves", brand: "Steelcase", tags: ["hands", "winter"] },
  { id: "4", title: "Safety glasses", brand: "Uvex", tags: ["eyes"] },
];

test("tolerates typos", () => {
  const fuse = buildSearch(items);
  const r = search(fuse, "hardhat visr");
  assert.equal(r[0].id, "2");
});

test("title weight beats brand and tag weight", () => {
  const fuse = buildSearch(items);
  // "steel" appears in a title (boots) and a brand (Steelcase); weighted title should rank first
  const r = search(fuse, "steel");
  assert.equal(r[0].id, "1");
  assert.ok(r.some((x) => x.id === "3"));
  assert.ok(r[0].score <= r[1].score);
  assert.ok(r[0].keys.includes("title"));
});

test("matches array tags", () => {
  const fuse = buildSearch(items);
  const r = search(fuse, "winter");
  assert.equal(r[0].id, "3");
  assert.deepEqual(r[0].keys, ["tags"]);
});

test("serialized index round-trips with same results", () => {
  const fuse = buildSearch(items);
  const restored = loadSearch(items, serializeIndex(fuse));
  assert.deepEqual(search(restored, "glasses"), search(fuse, "glasses"));
});

test("unrelated query returns nothing", () => {
  assert.deepEqual(search(buildSearch(items), "xylophone"), []);
});