Relative URLs are good, and most assets on the web can enjoy usage of them (images, videos, flash objects, EventSource, etc), but the WebSocket constructor does not support them.

Presumably this is due to requiring a ws or wss protocol, but I would pose that using http and https is actually fine for WebSockets, as it accurately represents the method by which they acquire a connection.

So all together:

• Allow WebSocket to use http(s) protocol URLs
• If not, still allow relative URLs by mapping the protocol instead of throwing