Autocomplete mentions, irc commands

[terrysahaidak]

In the web version, there are some types of suggestion showing in the pop-up above message input.

When users types @ sign, suggestion bar will show some users suggestion. By clicking on it, it will be applied to message input:

It uses https://gitter.im/api/v1/rooms/${id}/users?q=${query}&limit=10 endpoint to fetch suggestions for users.
Also, where is an additional command @/all that mentions all the users.

When users types / sign, it will display all available commands for that room:

if the user is an admin of the room, there are some additional commands:

Not all of commands are already implemented. See that code to get current state of available command list.