51help TIY
码：
<html> <head> <script type="text/javascript"> function timedMsg() { var t=setTimeout("alert('5 秒！')",5000) } </script> </head> <body> <form> <input type="button" value="警告框" onClick = "timedMsg()"> </form> <p>告框会在 5 </p> </body> </html>
查看结果: