[javascript] How to run function of parent window when child window closes?

I am calling the javascript window.open() function to load another url in a pop up. Once the users is finished it takes them to the last page that has a link that says close window that calls the window.close() function. Now when that page closes I need to update something in the original page that opened the window. Is there any way to do this? I have to call a function that is in my original page.

I know this post is old, but I found that this really works well:

window.onunload = function() {
    window.opener.location.href = window.opener.location.href;
};

The window.onunload part was the hint I found googling this page. Thanks, @jerjer!

You probably want to use the 'onbeforeunload' event. It will allow you call a function in the parent window from the child immediately before the child window closes.

So probably something like this:

window.onbeforeunload = function (e) {
    window.parent.functonToCallBeforeThisWindowCloses();
};

Along with jerjer answer(top), sometimes in your parent window and child window are not both external or both internal you will see a problem of opener undefined, and you cannot access parent page properties, see window.opener is undefined on Internet Explorer

Check following link. This would be helpful too..

In Parent Window:

function OpenChildAsPopup() {
        var childWindow = window.open("ChildWindow.aspx", "_blank",
        "width=200px,height=350px,left=200,top=100");
        childWindow.focus();
 }

function ChangeBackgroudColor() {
        var para = document.getElementById('samplePara');
        if (para !="undefied") {
            para.style.backgroundColor = '#6CDBF5';
        }
 }

Parent Window HTML Markup:

<div>
  <p id="samplePara" style="width: 350px;">
            Lorem ipsum dolor sit amet, consectetuer adipiscing elit.
  </p><br />
 <asp:Button ID="Button1" Text="Open Child Window" 
         runat="server" OnClientClick="OpenChildAsPopup();"/>
</div>

In Child Window:

// This will be called when the child window is closed.     
  window.onunload = function (e) {
        opener.ChangeBackgroudColor();
        //or you can do
        //var para = opener.document.getElementById('samplePara');
        //if (para != "undefied") {
        //    para.style.backgroundColor = '#6CDBF5';
        //}
    };

The answers as they are require you to add code to the spawned window. That is unnecessary coupling.

// In parent window
var pop = open(url);
pop.onunload = function() {
  // Run your code, the popup window is unloading
  // Beware though, this will also fire if the user navigates to a different
  // page within thepopup. If you need to support that, you will have to play around
  // with pop.closed and setTimeouts
}

This is an old post, but I thought I would add another method to do this:

var win = window.open("http://www.google.com");

var winClosed = setInterval(function () {

    if (win.closed) {
        clearInterval(winClosed);
        foo(); //Call your function here
    }

}, 250);

You don't have to modify the contents or use any event handlers from the child window.