The js pop-up box only pops up once (after the second modification)_javascript skills

The pop-up box only pops up once, and there are a lot of them written about it on the Internet, but there are not many that can actually be used. The following is my modified code for reference.

This code is controlled using cookies. First, the cookie is used to let the browser remember that this page has been opened once. If this page is referenced again, it will not be opened again. Proceed to open. Once the browser is closed, the cookie file saving this record will be deleted. Therefore, if you close the browser and open it again, the pop-up window will appear, thus ensuring that only one window is opened based on the original window.

Copy code The code is as follows: