Check if user closed the page in PHP?

Question

I made a chat using PHP and JavaScript chat and there is a disconnect button which removes user from the chat removing him from user list first. But if the user closes brows

Answer 1

Sorry, there is no reliable way of doing this, that's the way HTTP was built - it's a "pull" protocol. The only solution I can think of is that "valid" and logged in clients must query the server in a very small interval. If they don't, they're logged out.