node.js - How to detect when a user is viewing a webpage using javascript -

i have webpage want display users have page opened. (i'm using node.js server side)

my current attempt:

on server side, there's counter counts amount of time submits request webpage. hence if opens page more once, counter++

everytime user leaves webpage, sends websocket server using socket.io.

window.onbeforeunload = function() {      socket.emit('closepage'); } 

then on server side, when receives socket, decreases counter 1, a.k.a counter--

so using logic, it's possible detect when user has webpage opened , when closes webpage real.

however, problem occurs when user refreshes page crazy, server adds continuously counter without decreasing afterward, because window has not unloaded yet (my guess).

does know how fix stuffs this? or know algorithm forums use when display users or strangers reading post?

thanks lot!

you drop cookie , not increment count if cookie exists. or block on ip, might knock out genuine views.