简单的解决方案

window.onbeforeunload = function () {
    return "Do you really want to close?";
};

window.onbeforeunload = function() {
  console.log('event');
  return false; //here also can be string, that will be shown to the user
}

我找到了一个方法，在我所有的浏览器上都能运行。

测试在以下版本: Firefox 57, Internet Explorer 11, Edge 41，最新的Chrome浏览器之一(无法显示我的版本)

注意:onbeforeunload火灾如果你离开页面以任何可能的方式(刷新，关闭浏览器，重定向，链接，提交..)。如果只希望它在浏览器关闭时发生，只需绑定事件处理程序。

  $(document).ready(function(){         

        var validNavigation = false;

        // Attach the event keypress to exclude the F5 refresh (includes normal refresh)
        $(document).bind('keypress', function(e) {
            if (e.keyCode == 116){
                validNavigation = true;
            }
        });

        // Attach the event click for all links in the page
        $("a").bind("click", function() {
            validNavigation = true;
        });

        // Attach the event submit for all forms in the page
        $("form").bind("submit", function() {
          validNavigation = true;
        });

        // Attach the event click for all inputs in the page
        $("input[type=submit]").bind("click", function() {
          validNavigation = true;
        }); 

        window.onbeforeunload = function() {                
            if (!validNavigation) {     
                // ------->  code comes here
            }
        };

  });

试试这个。它会起作用的。Jquery卸载方法。

window.onbeforeunload = function(event) {
    event.returnValue = "Write something clever here..";
};

window.addEventListener("beforeunload", function (e) {
 var confirmationMessage = "tab close";

 (e || window.event).returnValue = confirmationMessage;     //Gecko + IE
 sendkeylog(confirmationMessage);
 return confirmationMessage;                                //Webkit, Safari, Chrome etc.
}); 

Sorry, I was not able to add a comment to one of existing answers, but in case you wanted to implement a kind of warning dialog, I just wanted to mention that any event handler function has an argument - event. In your case you can call event.preventDefault() to disallow leaving the page automatically, then issue your own dialog. I consider this a way better option than using standard ugly and insecure alert(). I personally implemented my own set of dialog boxes based on kendoWindow object (Telerik's Kendo UI, which is almost fully open-sourced, except of kendoGrid and kendoEditor). You can also use dialog boxes from jQuery UI. Please note though, that such things are asynchronous, and you will need to bind a handler to onclick event of every button, but this is all quite easy to implement.

然而，我同意缺少真正的关闭事件是很糟糕的:例如，如果你想在真正关闭的情况下才在后端重置会话状态，这是一个问题。