Let's rewrite my question:
I won't be providing any code because it would take too much of my paid work time to pull some code examples from my project. Most importantly, I think it has nothing to do with code and everything to do with browser/browser security.
When Chrome (or Edge) attempts to open an external application (no matter what the application is), an alert box pops up asking Chrome whether it should open the external application.
Whether I turn it on or dismiss the alert box, I no longer receive all socket.io communication from my backend server at this moment.
Everything works fine before trying to open an external application or after a page refresh.
This is my question, if I don't provide any code example some people may not understand the question, I apologize. I'm just hoping someone has already encountered this type of problem and knows how to fix it.
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
I managed to solve the problem. I open the link to the external application directly in a new tab, which transfers the alert box to the newly opened tab.
The alert box seems to be causing the error. My main tab can still receive signals from the backend when it's opened in another tab.
Thank you to everyone who encountered this problem^^