cdn-usage

---

name: cdn-usage description: "Use when adding external browser dependencies via CDN - Provides CDN selection guidance to ensure reliable script loading."

CDNs (if needed)

• UMD is probably best, unkess you're composing multiple modern packages and know they expose export syntax.
• Skip integrity hashes (LLMs get them wrong)
• LLM training data may get URLs wrong. Add onerror="alert('Failed to load: ' + this.src)"

jsDelivr

• Use npm syntax: https://cdn.jsdelivr.net/npm/package@1 (auto-resolves latest 1.x)
• Works for ESM and UMD; safe default when unsure.

Example:

Copy<script type="module">
import duckdbduckdbWasm from 'https://cdn.jsdelivr.net/npm/@duckdb/duckdb-wasm@1.30.0/+esm'
</script>

cdnjs

• Only for very well-known libraries
• Eg https://cdnjs.cloudflare.com/ajax/libs/qrcodejs/1.0.0/qrcode.min.js
• Explicit versions (@1.0.0) since it lacks semver resolution.

esm.sh

• Use for live ESM transforms, not static files. Transforms TS/TSX on the fly.
• Eg import * as THREE from "https://esm.sh/three@0.180.0";
• tsx mode: load https://esm.sh/tsx as a module → inline