Only if you use plain IRC. If you use something like irccloud, that is prevented. Which can be thought of as a "webwrapper" for IRC. I have been using it for some time now and I enjoy it.
(I'm not affiliated with irccloud in any way)
(I'm not affiliated with irccloud in any way)
I have been using Slack for about a year now at work and I think it's great. I don't think irccloud would be a suitable replacement either :-)