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Obtain reference to existing browser window

I'm 99% sure that the answer to my question will be no but just in case...
Use case:
Webpage A opens a new window B with JavaScript (same domain)
The user refreshes A or navigates away and then returns
The user clicks on a link in page A which should close B
This works fine by holding on to the window reference as long as the user does not refresh and navigates away from A (step 2).
Is there any (exotic or not) way to re-obtain the reference to the previously opened window(s) when returning to A?

Yes
function openWin() {
w = window.open("","windowname"); // use the window name you gave it when you opened it
if (w && !w.closed) ...
}

Access a window by window name

If I open a window using
window.open('myurl.html', 'windowname', 'width=100,height=100');
How do I refer to the new window (from the same page that opened it) using 'windowname'? This question is specifically about this. I'm aware that I could save a reference to the handle by using "var mywin = window.open(...)" but I don't care about that in this situation.
Thanks, - Dave

In firefox (might work in other browsers too, but now it's not my concern) I was able to reference one window accross multiple page loads with
var w = window.open("", "nameofwindow");
This opens new window if it doesn't exist and return reference to existing window if it does exist without changing contents of the window.
With jQuery I was then able to append new content, to make quick collection of interresting links like this
$('body', w.document).append(link_tag);

If you didn't save a reference to the window then there is no way to restore it. However, if that window is still open and if the page loaded there belongs to the same domain as your page, you can run JavaScript code in it:
window.open("javascript:doSomething()", "windowname");
Whether that's sufficient in your scenario depends on what you are trying to achieve.

Petr is correct:
var w = window.open("", "nameofwindow");
works in all browsers, I am using it to retrieve the reference to the window object previously opened by a different page. The only problem is the initial opening of the page, if the popup does not exist, you will get a new window with a blank page.
I tried invoking a Javascript function inside the context of the other document in order to check whether I opened a new window or retrieved the already active page. If the check fails, I just invoke window.open again to actually load my popup content:
var w = window.open("http://mydomain.com/myPopup", "nameofwindow");
Hope that helps.

It is not possible. The windowName is just to be used in target="..." of links/forms or to use the same name again in another window.open call to open a new url in that window.

Try open that window with the name, but URL is '' again, to check if it's a blank window or not. If it's in open, then you will get the window; if not, a new window open, and you need close it.
Add the children in localStorage will help to prevent to open the new blank window.
Please check my code in https://github.com/goldentom66/ParentChildWindow

Sorry I am posting late, but if you still have the other window open, and they are on the same domain, you can run, on the first window:
function getReference(w) {
console.log('Hello from', w);
}
And on the second window:
window.opener.getReference(window);

afaik there's no way like windows['windowname'].
The 'windowname' assigned in window.open() can be addressed as a target in <a target="windowname" [...] >

Javascript Popup Window as a singleton

I have a page A which opens a javascript window as myWin = window.open(..). Now in another page B in the same domain, when user clicks on a link, I want to check if myWin is available, if yes then bring that window in front, else do a new myWin.
The problem I have is the window.js file in both pages and window.js contains the line
var myWin = null;
Within Page A scope, my logic works and brings window to front. Within Page B it works as well. Howver when I open window in Page A, click on link in Page B, it fails.
It is as if myWin is reset to null in scope of Page B. How can I overcome this problem? Pointers??/

The popup window is created by page A and only page A contains a reference to that window. When you open page B, there is no way to pass page A's reference to the popup over to page B. This cannot be done.

You want to call window.open with an empty url, e.g.
var newWindow = window.open('', title, dimension); // title needs to be a constant
if (newWindow.location.href && newWindow.location.href!='about:blank') {
// Window was already open and points to something
newWindow.focus();
} else {
// new window make it point to something
newWindow.location.href = 'http://yoursite';
}
This assumes that the popup is opening a window within the same site as the calling page, since otherwise you can encounter various permissions issues.

javascript refresh popup from another popup

Window A opens window B
Window A opens window C
On Window C (after user action) I need Window B refreshed.
some more explanation:
yes. Window A is the main calendar. window B is opened manually and is smaller and shows stats about the calendar (window A)
When user clicks on a calendar event in window A then Window C opens. And when the user changes info on Window C then Window B (stats) needs to update.

First of all I have to warn you that what you are trying to achieve is not a good practice.
Many browsers are opening new tabs instead of new windows, which can influence the availability of the window.opener . Although this depends heavily on the browser settings.
So first of all you should test to see that your code is really opening new windows, not new tabs.
Now, in a.html you should have this:
var windowB=window.open("b.html");
var windowC=window.open("c.html");
In c.html you should have this:
function openNewPage() {
window.opener.windowB.location.reload(true);
}
and call the openNewPage() function on user interaction.

You need to set references to each other the child windows to each other. Here's a simple demo.
var b= window.open('');
var c= window.open('');
b.test=function() {
alert('Function in window B');
};
c.test=function() {
b.test();
return false;
};
$(b.document).find('body').append('<div>Window B. Click here</div>');
$(c.document).find('body').append('<div>Window C. Click here</div>');
http://jsfiddle.net/9ZCX3/25/

Find window previously opened by window.open

We've got the following situation, running from a single domain:
Page A uses window.open() to open a named window (a popup player). window.open() gives page A a reference to the window.
User now reloads page A. The reference to the named window is lost. Using window.open() to "find" the window has the unfortunate side effect of reloading it (undesirable). Is there any other way to get a reference to this window?

Try this:
var playerUrl = 'http://my.player...';
var popupPlayer= window.open('', 'popupPlayer', 'width=150,height=100') ;
if(popupPlayer.location.href == 'about:blank' ){
popupPlayer.location = playerUrl ;
}
popupPlayer.focus();
It will open a blank window with a unique name. Since the url is blank, the content of the window will not be reloaded.

AFAIK, no there isn't..
A kind-of-dirty-but-i-guess-it-will-work hack would be to periodically reset the reference on the parent window from within the popup using window.opener, with something like this code:
setInterval(function() {
if(window.opener) {
window.opener.document.myPopupWindow = window
}
}, 100)
In the parent window, you'll be able to access document.myPopupWindow, even after a reload (well, 100ms after the reload). This should work cross browser.

Actually what you did is destroy the parent (page A) of the created window (Popup), so it has no more reference to the original parent therefore you can't get a direct reference.
The only solution I can think of is using a browser that offers you added javascript capability to cycle through active windows (tabs) and find one that has a special property (ie: your reloaded page A) that gets recognized by the popup.
Unfortunately I guess only firefox has some added capability or extension that gives you this flexibility. (it is also a security risk though)

This should work. Add this code in the popup:
function updateOpener() {
if (window.opener)
window.opener.document.myPopupWindow = window;
else
setTimeout(updateOpener, 100);
}
updateOpener();
And this in onload of the parent window. To make sure myPopupWindow have been set wait 100 ms before accessing it.
setTimeout(function() {
if (document.myPopupWindow)
document.myPopupWindow.focus();
}, 100);

If all the windows share a common Url origin you can register a ServiceWorker and then access all windows from the ServiceWorker: https://developer.mozilla.org/en-US/docs/Web/API/Clients
AFAIK You won't be able to pass a reference to other windows from WorkerService to your window but you can establish communications with the ServiceWorker via
https://developer.mozilla.org/en-US/docs/Web/API/Worker/postMessage
https://developer.mozilla.org/en-US/docs/Web/API/Client/postMessage

It Might help someone, If you opened an child tab and after refreshing the parent tab, you still want to focus on that child tab instead of opening new child tab: -
const chatPopup = window.open('', 'chatPopup');
if (chatPopup.location.href === 'about:blank' || !chatPopup.location.href.includes('/chat')) {
this.openNewWindow = window.open('/chat', 'chatPopup');}