TogetherJS (https://togetherjs.com/) provides a way for an open source project to connect users, peer-to-peer, and provides: usernames, user colors, avatars, and a chat log. It operates like a JS library, just something you add to a page, rather than a framework that dictates the tech stack.

Glossing over some nuance, it's now abandonware.

What's an alternative? Socket.io doesn't seem to come with the above-mentioned batteries included.