Sure you can use hooks on the client side, but server side and client side hooks are separate. Something that fires on the server side doesn't automatically fire client side.
You have to look in the client side code in the public folder to see if the hook you need exists. In the chat message case there is action:chat.sent which you can use to modify the message before being sent to the server. https://github.com/NodeBB/NodeBB/blob/master/public/src/client/chats/messages.js#L21
