Friends who are often online may have come so some websites, one window will pop up, or press a connection or button to pop up, usually display some precautions, copyright information, warnings, welcome to this window. Or the author wants a special tip. In fact, it is easy to make such a page effect. Just join several JavaScript code to the HTML of the page. Let's take you the mystery of it.
[1, the most basic pop-up window code]
In fact, the code is very simple:
