Yes, I've seen those 'traps" a few times recently, BUT......A note of caution regarding clicking on the 'buttons' in the alert, pop-up, etc.
You CAN NOT trust any of the buttons, etc., to do what they usually represent (such as the Cancel button), they can be programmed to do something malicious. Of course they do this knowing that the average user will try the normal buttons to close it out, etc.
The best procedure to use for Windows OSes is to use Ctrl + Alt + Del and click on the Task Manager button to open the Task Manager and then the Applications tab so you can cancel (close out) the browser that you're using for that site.
I don't know the equivalent for a Linux OS, or for Macs.