Like others have said, it's going to be a new package registry. It was unofficially announced at SeattleJS Conf 2023: https://www.youtube.com/watch?v=Dkqs8Mcxbvo&t=424s

I didn't see any major reason for why they were creating another registry.

I thought their whole thing was to maintain backwards compatibility, not introduce new, redundant standards?

Here's the specific talk https://youtube.com/watch?t=822&v=dipwQfcV0AU (CascadiaJS channel) or https://youtube.com/watch?t=822&v=5DX49vzLfqw (Deno channel)

JSR = JavaScript Registry (from the site). It seems fairly clear this is a package registry, i.e. an NPM alternative.

But they promoted they will not need one at any time, to extent they will never build one. There was only deno.land as a point to discover libraries or what community builds.

Yep, but it seems they learned something from the experience?

Hopefully it will be closer to how Go does it.

Hmm, curious too. Maybe, given the few hints, an alternative to npmjs.com registry.

I assume it's an npm competitor? Likely with a different technical design.

Here's what they have to say on the JSR site:

Why Choose JSR? A True TypeScript-First Environment: Efficient type checking and no transpilation hassles—write in TypeScript and deploy directly.

Performance and Usability at the Forefront: With integrated workspaces and seamless NPM integration, JSR puts usability first.

Secured and Accessible Modules: All modules in JSR are exposed over HTTPS, ensuring your code is always secure.

Open Source, Community-Driven: Built by developers, for developers, JSR is shaped by the real-world needs and contributions of the JavaScript community.