新窗口打开
<select onchange="window.open(this.options[this.selectedIndex].value)" name="select">
<option http://www.microsoft.com/ie">http://www.microsoft.com/ie
<option http://www.microsoft.com%22%3emicrosoft/">http://www.microsoft.com">Microsoft
<option http://msdn.microsoft.com%22%3edeveloper/">http://msdn.microsoft.com">Developer
</select>
原窗口打开
<select onchange="location.href(this.options[this.selectedIndex].value)" name="select">
