IndexedDB adapter fails in Web Workers because distributed bundle resolves IndexedDB from `window.indexedDB`

Author: Wxh16144Created Jun 1, 2026Updated Jun 1, 2026

[email protected] fails when using the persistent IndexedDB adapter inside a Web Worker / module worker.

The failure happens because the distributed IndexedDB adapter resolves IndexedDB from window.indexedDB at module initialization time:

javascript

const Bb = typeof window !== "undefined" &&
  (window.indexedDB ||
   window.mozIndexedDB ||
   window.webkitIndexedDB ||
   window.msIndexedDB)

Later, the adapter calls:

javascript

Bb.open(...)

In a Web Worker, window is not available. IndexedDB is available via globalThis.indexedDB or self.indexedDB, but not via window.indexedDB.

As a result, Bb is not a valid IDBFactory, and opening the database fails.

Runtime Error

Error: Bb.open is not a function

Package Version

[email protected]

Relevant Package Entry Points

From the published package.json:

json

{
  "main": "dist/flexsearch.bundle.min.js",
  "module": "dist/flexsearch.bundle.module.min.mjs",
  "exports": {
    ".": {
      "types": "./index.d.ts",
      "import": "./dist/flexsearch.bundle.module.min.mjs",
      "require": "./dist/flexsearch.bundle.min.js"
    },
    "./db/*": {
      "import": "./dist/module/db/*/index.js",
      "require": "./dist/db/*/index.cjs"
    }
  },
  "browser": {
    "dist/flexsearch.bundle.module.min.js": "./dist/flexsearch.bundle.module.min.mjs"
  }
}

The published dist/flexsearch.bundle.module.min.js contains this worker-incompatible IndexedDB lookup (line 94):

javascript

const Bb = typeof window !== "undefined" &&
  (window.indexedDB ||
   window.mozIndexedDB ||
   window.webkitIndexedDB ||
   window.msIndexedDB)

The source file also uses window:

javascript

const IndexedDB = typeof window !== "undefined" && (
    window.indexedDB ||
    window.mozIndexedDB ||
    window.webkitIndexedDB ||
    window.msIndexedDB
);

Reference: https://github.com/nextapps-de/flexsearch/blob/f7ed963096a0792da7b2fd63bb7114b3fbac55ed/src/db/indexeddb/index.js#L15-L30

Environment

FlexSearch version: 0.8.212
Runtime: browser Web Worker / module worker
Bundler: webpack
Browser environment: Chromium / Electron renderer
IndexedDB availability in worker:
- globalThis.indexedDB: ✅ available
- self.indexedDB: ✅ available
- window: ❌ not defined

Minimal Reproduction

worker.js:

javascript

import * as FlexSearch from "flexsearch";

const index = new FlexSearch.Document({
  document: {
    id: "id",
    index: ["title", "content"],
    store: true
  },
  commit: false
});

const storage = new FlexSearch.IndexedDB("flexsearch-worker-test");

await index.mount(storage);
await index.db;

await index.add({
  id: "1",
  title: "hello",
  content: "world"
});

await index.commit();

self.postMessage("done");

Main thread:

javascript

const worker = new Worker(new URL("./worker.js", import.meta.url), {
  type: "module"
});

worker.addEventListener("message", console.log);
worker.addEventListener("error", console.error);

Expected Behavior

The IndexedDB persistent adapter should work inside a Web Worker when IndexedDB is available through globalThis.indexedDB or self.indexedDB.

Actual Behavior

The adapter resolves IndexedDB from window.indexedDB.

Since window is not defined in Web Workers, the internal IndexedDB reference (Bb) is invalid and opening the database fails:

Error: Bb.open is not a function

Source: nextapps-de/flexsearch

View original on GitHub View discussion on GitHub