- When a project reaches a popularity threshold (for example 10k github stars or gets to be the most popular project is his category - example: the most popular 3D library) would get a subdomain:

https://jquery.js.org/eachplugin

https://node.js.org/express

When we get exceptions, in this case, express grew and got autonomous, https://node.js.org/express would redirect to:

https://express.js.org/