The gorilla websocket library does not support webassembly. It would be nice to use https://github.com/nhooyr/websocket to have support for it. It would require test to make sure it also work with gopherjs, if it doesn't a follow up story should be created and some logic could be added to switch between libraries depending on the platform.
After investigating more, we should drop gorilla as it is just unmaintained for almost 4 years and they have not figure out a replacement. The above one seems in a better position (considering client API only).
The gorilla websocket library does not support webassembly. It would be nice to use https://github.com/nhooyr/websocket to have support for it. It would require test to make sure it also work with gopherjs, if it doesn't a follow up story should be created and some logic could be added to switch between libraries depending on the platform.