Caution
This library is deprecated.
Use "mmdb-lib" directly instead.
The code below works in a browser - no transpilation needed. Just wrap it in <script type="module">...</script> and drop it as is in your HTML.
import { Buffer } from 'https://esm.run/buffer';
import { Reader } from 'https://esm.run/mmdb-lib';
const response = await fetch(
'https://raw.githubusercontent.com/maxmind/MaxMind-DB/main/test-data/GeoLite2-Country-Test.mmdb',
);
const buffer = Buffer.from(await response.arrayBuffer());
const reader = new Reader(buffer);
console.log(reader.get('89.160.20.122'));