Real time - Which is the best way?

How large is your user base?

Depending on what kind of functionality, how large your active user base is,  and how 'real-time' you need it to be, you can choose between polling or websockets.

At the end of the day, websockets will scale much better than polling and is more real-time. If you're wanting to go the easy route of websockets, I'd recommend nodejs with something like socket.io. If you're wanting to build an app that can scale to the roof, I'd recommend using Elixir + phoenix.

My website still under construction, I'm at the point to do the real time. I know that websockets are not available on all browser, is it a problem?

However, I'll see elixir and phoenix because I don't know them.
Obviously I'm using Codeigniter to build the website's system.