window.opener.focus() doesn't work

From the fine manual:

Makes a request to bring the window to the front. It may fail due to user settings and the window isn't guaranteed to be frontmost before this method returns.

Emphasis mine. Calling focus() is just a request and the browser is free to ignore you and you should generally expect to be ignored. Consider what sorts of nefarious things you could get up to by switching focus to a tiny window while someone is typing if you need some reasons why a browser would ignore your request.

If you need focus() to work for your application to work then you need to redesign your application so that it doesn't need to call focus().

I can see why a browser/OS will not allow a child windows to take over the focus (abuse of power). Here is a workaround:

1. In the parent window, declare a function in "window.external" that will trigger Javascript "alert()" or "confirm()".
2. Invoke that function from the child window.
3. The browser might ignore a request from a child window that wants to control the focus (e.g. window.opener.focus()), but the browser should honor a request from a parent window that triggers an alert() or a confirm() action, which requires to focus on the parent window.

JS Parent:

    var child = window.open('child.html', 'child');
    window.external.comeback = function() {
        var back = confirm('Are you sure you want to comback?');
        if(back) {
            child.close();
        } else {
            child.focus();
        }
    }

JS Child:

    // assuming you have jQuery
    $('.btn').click() {
        window.opener.external.comeback();  
    };

--I am using this code in a real world application to handle a checkout request that runs in child window, and I need to gracefully return to the parent window.

See: SimplifySites.com