Foreword: Regular online friends may have arrived in some websites, one window will pop up, or press a connection or button to pop up, usually there will be some precautions, copyright information, warning, welcome to this window. Class or the author wants a special prompt. In fact, it is easy to make such a page effect. Just join several JavaScript code to the HTML of the page. Below I will take you to the mystery of it.
[1, the most basic pop-up window code]
