Let's talk about jQuery and Google Chrome's closing events

With the continuous enhancement of web page functions, more and more web pages need to monitor and process user behavior. Among them, one of the most common behaviors is that the user closes the browser window. However, the implementation of this functionality may vary slightly in different browsers. Today, let’s discuss how jQuery handles window closing events in Google Chrome.

1. The unload event of window

The window closing event can actually be realized through the unload event of the window object. The unload event is triggered when the window or frame is unloaded. The following is an example of using pure JavaScript to implement a window closing event:

window.onunload = function() { alert("窗口即将关闭！"); }

In this example, when the browser window is closed, a prompt box will pop up to remind the user of the occurrence of the event. However, there is a problem with using the unload event: it is also triggered when the browser jumps to other pages. Therefore, if any link in the page is clicked, the unload event will also be triggered. This often causes problems for programmers.

2. jQuery’s unload event

In order to solve the problem of unload event, jQuery provides its own unload event. It only fires when the browser window is closed, not when the browser jumps to another page. The following is an example of using jQuery to implement a window closing event:

$(window).on("unload", function() { alert("窗口即将关闭！"); });

In this example, the $(window) selector selects the window object, and then uses the on() method to bind the unload event. When the window is closed, a prompt box will pop up.

3. Special processing of Google Chrome

Although jQuery's unload event can work normally in most browsers, there is a special situation that needs attention in Google Chrome.

In Google Chrome, if the web page contains any running plug-ins (such as Flash), when the user closes the browser, the process in which the plug-in is located will not exit immediately, but will take some time. to end. In this case, the unload event may not be fired.

To solve this problem, we can use the beforeunload event. This event is fired before the window is closed, and the window closing event can be canceled by returning a string. The following is an example of using the beforeunload event in Google Chrome:

$(window).on("beforeunload", function() { return "确定要离开吗？"; });

In this example, when the user closes the browser, a prompt box will pop up asking the user if they are sure they want to leave. If the user clicks the "Cancel" button, the browser will not be closed.

It should be noted that if the web page contains a running plug-in, in Google Chrome, even if the beforeunload event is used, the window closing event cannot be completely accurately captured. Therefore, in practice, you should try to avoid any running plug-ins in your web pages.

Conclusion

Through the above discussion, we can draw the following conclusion:

1. You can use the unload event of window to implement the window closing event, but it will also Fired when the browser jumps to another page.
2. In jQuery, you can use the unload event to implement the window closing event. It only fires when the browser window is closed, not when the browser jumps to another page.
3. In Google Chrome, if the web page contains a running plug-in, the unload event may not be triggered. At this point, you can use the beforeunload event to ask the user if they are sure they want to close the window.

In short, implementing the window closing event requires special processing for different browser environments. In practice, we should choose the appropriate event handling method according to the specific situation and fully test various situations.

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