Track multiple window closes javascript (Have working code for one window)

Question

Does someone know the best solution to make the code below work ('crosswindow') to track multiple windows opened by the function openNew() ?

It is currently only capable of tracking one window only. I tried some stuff with objects but Im not an expert. All suggestions are welcome.

Javascript:

 function openNew(href){

    timer = setInterval('polling()',500);
    win = window.open(href, '_blank');

    url=href;
    openTime=0;
    clickTime= (new Date()).getTime();

}

function polling(){

     if (win && win.closed) {

        var closingTime = (new Date()).getTime();
        var diff = ((closingTime-clickTime)/1000);

        clearInterval(timer);
        console.log(url+" closed after " + diff + " secs");
    }  
}

HTML

<a href="http://google.com" onClick="openNew('http://google.com'); return false;" target="_blank">google</a>
<a href="https://facebook.com" onClick="openNew('https://facebook.com'); return false;" target="_blank">facebook</a>

The goal in the end is to be able to open multiple new windows from the parent page and when a child window gets closed, its logged in the parent window.

I have made a pen with a simulation of the console (to avoid infinity loop alerts ) http://codepen.io/anon/pen/EjGyQz?editors=101

Answer 1

So, you just need to wrap your call to polling in a closure, and pass in all of the variables to it, so it isn't overwriting the old ones:

http://codepen.io/anon/pen/GJPqwm?editors=101

function openNew(href){
    var current = window.open(href, '_blank');
    var clickTime= (new Date()).getTime();
    (function(win, url, clickTime) {
        var timer = setInterval(function() { polling(win, timer, url, clickTime) },500);
    })(current, href, clickTime);       
}

function polling(win, timer, url, clickTime){
     if (win && win.closed) {
        var closingTime = (new Date()).getTime();
        var diff = ((closingTime-clickTime)/1000);
        clearInterval(timer);
        //replace console with div log
        document.getElementById('log').innerHTML += url+" closed after " + diff + " secs<br>";
    }  
}