使用本地存储，我创建了一个简单的演示，该演示应可以完成您的工作。基本上，它只是维护当前打开的窗口的数量。当窗口关闭时，将触发卸载事件，并将其从总窗口数中删除。

当您初看它时，您可能会认为发生的事情比实际更多。多数是为了将逻辑添加到谁是“主”窗口中，以及在关闭孩子时谁应该接管“主”窗口中的尝试。（因此，setTimeout调用以重新检查是否应将其提升到主窗口）
在抓了一些头之后，我认为实现起来将花费太多时间，并且超出了此问题的范围。
但是，如果您打开两个窗口（“主窗口”和“子窗口”）并关闭了“主窗口”，则该子窗口将升级为主窗口。

在大多数情况下，您应该能够大致了解发生的事情并将其用于自己的实现中。

哦，是的，实际上可以看到它的作用…在多个窗口中打开链接。:)

更新：

我已经进行了必要的更改，以使本地存储维护“主”窗口。关闭选项卡后，子窗口便可以升级为主窗口。有两种方法可以通过传递给WindowStateManager的构造函数的参数来控制“主”窗口状态。这个实现比我以前的尝试要好得多。

JavaScript：

// noprotect

var statusWindow = document.getElementById('status');

(function (win)
{
    //Private variables
    var _LOCALSTORAGE_KEY = 'WINDOW_VALIDATION';
    var RECHECK_WINDOW_DELAY_MS = 100;
    var _initialized = false;
    var _isMainWindow = false;
    var _unloaded = false;
    var _windowArray;
    var _windowId;
    var _isNewWindowPromotedToMain = false;
    var _onWindowUpdated;


    function WindowStateManager(isNewWindowPromotedToMain, onWindowUpdated)
    {
        //this.resetWindows();
        _onWindowUpdated = onWindowUpdated;
        _isNewWindowPromotedToMain = isNewWindowPromotedToMain;
        _windowId = Date.now().toString();

        bindUnload();

        determineWindowState.call(this);

        _initialized = true;

        _onWindowUpdated.call(this);
    }

    //Determine the state of the window 
    //If its a main or child window
    function determineWindowState()
    {
        var self = this;
        var _previousState = _isMainWindow;

        _windowArray = localStorage.getItem(_LOCALSTORAGE_KEY);

        if (_windowArray === null || _windowArray === "NaN")
        {
            _windowArray = [];
        }
        else
        {
            _windowArray = JSON.parse(_windowArray);
        }

        if (_initialized)
        {
            //Determine if this window should be promoted
            if (_windowArray.length <= 1 ||
               (_isNewWindowPromotedToMain ? _windowArray[_windowArray.length - 1] : _windowArray[0]) === _windowId)
            {
                _isMainWindow = true;
            }
            else
            {
                _isMainWindow = false;
            }
        }
        else
        {
            if (_windowArray.length === 0)
            {
                _isMainWindow = true;
                _windowArray[0] = _windowId;
                localStorage.setItem(_LOCALSTORAGE_KEY, JSON.stringify(_windowArray));
            }
            else
            {
                _isMainWindow = false;
                _windowArray.push(_windowId);
                localStorage.setItem(_LOCALSTORAGE_KEY, JSON.stringify(_windowArray));
            }
        }

        //If the window state has been updated invoke callback
        if (_previousState !== _isMainWindow)
        {
            _onWindowUpdated.call(this);
        }

        //Perform a recheck of the window on a delay
        setTimeout(function()
                   {
                     determineWindowState.call(self);
                   }, RECHECK_WINDOW_DELAY_MS);
    }

    //Remove the window from the global count
    function removeWindow()
    {
        var __windowArray = JSON.parse(localStorage.getItem(_LOCALSTORAGE_KEY));
        for (var i = 0, length = __windowArray.length; i < length; i++)
        {
            if (__windowArray[i] === _windowId)
            {
                __windowArray.splice(i, 1);
                break;
            }
        }
        //Update the local storage with the new array
        localStorage.setItem(_LOCALSTORAGE_KEY, JSON.stringify(__windowArray));
    }

    //Bind unloading events  
    function bindUnload()
    {
        win.addEventListener('beforeunload', function ()
        {
            if (!_unloaded)
            {
                removeWindow();
            }
        });
        win.addEventListener('unload', function ()
        {
            if (!_unloaded)
            {
                removeWindow();
            }
        });
    }

    WindowStateManager.prototype.isMainWindow = function ()
    {
        return _isMainWindow;
    };

    WindowStateManager.prototype.resetWindows = function ()
    {
        localStorage.removeItem(_LOCALSTORAGE_KEY);
    };

    win.WindowStateManager = WindowStateManager;
})(window);

var WindowStateManager = new WindowStateManager(false, windowUpdated);

function windowUpdated()
{
    //"this" is a reference to the WindowStateManager
    statusWindow.className = (this.isMainWindow() ? 'main' : 'child');
}
//Resets the count in case something goes wrong in code
//WindowStateManager.resetWindows()

HTML：

<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>JS Bin</title>
</head>
<body>
  <div id='status'> 
    <span class='mainWindow'>Main Window</span>
    <span class='childWindow'>Child Window</span>
  </div>
</body>
</html>

CSS：

#status
{
  display:table;
  width:100%;
  height:500px;
  border:1px solid black;
}
span
{
  vertical-align:middle;
  text-align:center; 
  margin:0 auto;
  font-size:50px;
  font-family:arial;
  color:#ba3fa3;  
  display:none;
}

#status.main .mainWindow,
#status.child .childWindow
{
  display:table-cell;
}

.mainWindow
{
  background-color:#22d86e;
}
.childWindow
{
  background-color:#70aeff;
}