Multiple esm.sh imports duplicate large dependencies (e.g. three), feature request: grouped external/shared modules

[vladkrutenyuk]

Hi 👋

I’ve noticed a problem when importing multiple libraries through esm.sh:
• Each import URL bundles its own dependencies.
• If two or more libraries share the same dependency, the browser still downloads it multiple times.
• For small deps this is fine, but for large ones (like three) it’s a big issue.

import * as THREE from "https://esm.sh/three";

import { OrbitControls } from "https://esm.sh/three/examples/jsm/controls/OrbitControls.js";
import { GLTFLoader } from "https://esm.sh/three/examples/jsm/loaders/GLTFLoader.js";

In this case, each addon import pulls in its own copy of three, so the browser downloads the same dependency multiple times.

I know there’s the ?external=three option to avoid bundling, but this still requires configuring every addon import manually.

Feature request

Would you consider adding a way to declare multiple npm modules in a single esm.sh URL, so esm.sh can resolve them together and avoid duplicating shared dependencies?

For example something like:

import {
  OrbitControls,
  GLTFLoader
} from "https://esm.sh/group?pkg=three/examples/jsm/controls/OrbitControls,three/examples/jsm/loaders/GLTFLoader&external=three";

This would make it easier to import addons/plugins that share a heavy dependency, without repeating ?external=... for every import.

Is this something you are considering, or maybe there’s already a recommended solution?

Thanks! 🙏

[ije]

i'm working on a CLI tool that manages import maps like npm, features include adding ?external automatically.

esm.sh add three

you will get an importmap script in your root index.html:

<script type="importmap">
  {
    "imports": {
      "three": "https://esm.sh/*three@0.179.1",
      "three/": "https://esm.sh/*three@0.179.1/",
    }
  }
</script>

*three means external all deps.