"Multiple instances of Three.js being imported" from CDN

Describe the bug

Three r125 now checks if multiple different instances of the library are being imported. Weirdly, though, this is already triggered simply by following the “Installation” section of the documentation:

<script type="module">
  import * as THREE from "https://unpkg.com/three/build/three.module.js";
  import { OrbitControls } from "https://unpkg.com/three/examples/jsm/controls/OrbitControls.js";
  /* Warning triggered */
</script>

Here’s a Codesandbox with the issue: https://codesandbox.io/s/three-multiple-instances-warning-nkfc9

I’ve tried a bunch of other ESM CDNs (skypack and jspm, specifically), with the same results.

To Reproduce

1. Visit the codesandbox
2. Check the console output

Code

See above.

Live example

• https://codesandbox.io/s/three-multiple-instances-warning-nkfc9

Expected behavior

There should not be a warning that multiple instances are being imported if they’re being imported via JS modules from CDNs.

Platform:

• Three.js version: [r125]

[hmans]

I’m unsure about this issue. It seems to me the mentioned problem is a general JavaScript thing. Or is there a concrete suggestion for a change in three.js?

The bug is that this happens when following the official instructions on the website. As @donmccurdy already pointed out, it could be argued that this is a bug with the documentation, not the library itself.

[donmccurdy]

Hmm, the warning is correct. From the network tab, with cache enabled:

Note that unpkg redirects unpkg.com/three to unpkg.com/three@0.125.1. It seems like even though the two references to three.module.js resolve to the same file, the browser is importing it twice. This does not happen if we use the versioned CDN URL instead, avoiding the redirect:

import * as THREE from "https://unpkg.com/three@0.125.1/build/three.module.js";
import { OrbitControls } from "https://unpkg.com/three@0.125.1/examples/jsm/controls/OrbitControls.js";
/* Warning NOT triggered */

Seems like we need to ensure the documentation uses version-pinned URLs, then?