Check if window is already open window.open

Question

I have a html page. In the body of the page I am calling onload event which calls javascript function to open a pop up window. here is the code:

var newWindow = null;
function launchApplication()
{
    if ((newWindow == null) || (newWindow.closed))
    {
        newWindow = window.open('abc.html','','height=960px,width=940px');
    }
}

when I move to another page, and come back to that page again, popup reopens, although it is already opened. Please guide me to proper direction so that if pop up is already open then it should not open again. I tried document.referred but it requires the site online, currently I am working offline.

that is because when you move to another page the newWindow reference is not accessible any more. When you move back to the page the newWindow is initialised to null and you get a new popup. I am afraid there is nothing you can do using javascript or any client side technology. Any one with a different idea? — MaVRoSCy, Aug 27 '12 at 08:08
@MaVRoSCy how would a server do what's clearly a matter of the client? If there's a server-side tech that does it, then we need to file security reports and work to shut it down. — Jon Hanna, Aug 27 '12 at 08:11
@Jon Hanna yes this is possible, using session variables to know if the popup is open. Using ajax you can check that session variable and when returning using a javascript function you can choose to open or not the popup based on the return of the AJAX call — MaVRoSCy, Aug 27 '12 at 08:50
@MaVRoSCy yes, but you were saying it couldn't be done on the client and then suggest a way that you can do it "server side" that involves the client. It wouldn't work anyway as it won't know if the window was closed, nor obtain a reference to the window if it is open (they may want to open a different resource or use `newWindow` in some way). They're much better of just doing it the normal client-side way. — Jon Hanna, Aug 27 '12 at 09:00
i was searching it thoroughly, so far concluded that it aint possible!!! without involving server.. and still there will be problem, if the window is closed, thn i have no way to knw, either it is closed or not, so that to reopen window again — Saghir A. Khatri, Aug 27 '12 at 09:08
@Jon Hanna you can use window.onunload to notify the server of any change in the popup state isn't it? — MaVRoSCy, Aug 27 '12 at 09:08

Jon Hanna · Accepted Answer · 2012-08-27T09:21:28.980

22

newWindow = window.open('abc.html','com_MyDomain_myWindowForThisPurpose','height=960px,width=940px');

Give the window a name. Basing the name on your domain like this, prevents the chances of you picking a name someone else happened to choose.

Never make up a name that begins with _, those are reserved for special names the browser treats differently (same as with the "target" attribute of anchor elements).

Note that if the window of that name was opened with different options (e.g. different height), then it'll keep those options. The options here will only take effect if there is no window of that name, so you do create a new one.

Edit:

Note that the "name" is of the window, not of the content. It doesn't affect the title (newWindow.document.title will affect that, as of course will code in abc.html). It does affect other attempts to do stuff across windows. Hence another window.open with the same name will reuse this window. Also a link like <a href="def.html" target="com_MyDomain_myWindowForThisPurpose">clicky!</a> will re-use it. Normal caveats about browsers resisting window-opening in various scenarios (popup-blocking) apply.

edited Aug 27 '12 at 09:21

answered Aug 27 '12 at 08:08

Jon Hanna

110,372
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1

its basically an instruction to name the title, and it will reopen the window. – Saghir A. Khatri Aug 27 '12 at 09:12
@SaghirA.Khatri Really, what browser did you find that happened in? – Jon Hanna Aug 27 '12 at 09:15
Worth noting that it's got nothing to do with the title, I'll edit to add a note on that. – Jon Hanna Aug 27 '12 at 09:19
it was actually my fault, i didn't noticed that with full attention,Well thanks, hope u never mind. :) – Saghir A. Khatri Aug 27 '12 at 09:20
1

NP. I was just confused that it wasn't working, javascript can always have "except in these browsers..." but this worked in NN2, the first javascript browser, so I thought maybe some new popup-blocking was interfering. – Jon Hanna Aug 27 '12 at 09:22
Is there any option to point to the already opened window as well as on button click? – ranjenanil Dec 13 '13 at 07:35
@ranjenanil, sorry I don't know what you mean there – Jon Hanna Dec 13 '13 at 10:02
i mean is there any option to focus the pop up page when clicking the button – ranjenanil Dec 13 '13 at 10:58

Timo Huovinen · Answer 2 · 2022-07-18T19:30:59.160

To open a window and keep a reference to it between page refresh.

var winref = window.open('', 'MyWindowName', '');
if(winref.location.href === 'about:blank'){
    winref.location.href = 'http://example.com';
}

or in function format

function openOnce(url, target){
    // open a blank "target" window
    // or get the reference to the existing "target" window
    var winref = window.open('', target, '');

    // if the "target" window was just opened, change its url
    if(winref.location.href === 'about:blank'){
        winref.location.href = url;
    }
    return winref;
}
openOnce('http://example.com', 'MyWindowName');

score 8 · Answer 3 · answered Oct 12 '16 at 08:43

You can check if the window is open or closed by re-assigning a reference to it when it closes. Example:

var newWindow;
var openWindow = function(){
    newWindow = newWindow || window.open('newpage.html');
    newWindow.focus();
    newWindow.onbeforeunload = function(){
        newWindow = null;
    };
};

score 1 · Answer 4 · answered Aug 04 '20 at 08:42

1

Use the "closed" property: if a window has been closed its closed property will be true. https://developer.mozilla.org/en-US/docs/Web/API/Window/closed

answered Aug 04 '20 at 08:42

Paul Swennenhuis

11
1

score 0 · Answer 5 · answered Jun 07 '18 at 09:13

When you move on another page (on the same domain), you can re-set the window.open variable with popup page like this :

https://jsfiddle.net/u5w9v4gf/

Step to try :

Click on Run (on jsfiddle editor).
Click on Try me (on preview).
Click on Run to move on another page, the variable will be re-set.

Code :

window.currentChild = false;

$("#tryme").click(function() {
    if (currentChild) currentChild.close();
    const child = window.open("about:blank", "lmao", 'width=250,height=300');
    currentChild = child;

    //Scrope script in child windows
    child.frames.eval(`
    setInterval(function () {
        if (!window.opener.currentChild)
            window.opener.currentChild = window;
    }, 500);
  `);
});


setInterval(function() {
console.log(currentChild)
    if (!currentChild || (currentChild && currentChild.closed))
        $("p").text("No popup/child. :(")
    else
        $("p").text("Child detected !")
}, 500);

Check if window is already open window.open

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