引用:http://zhidao.baidu.com/question/88934003.html
提示:把代码保存为a.htm即可预览效果 <script> function setDivBG(s) { document.getElementById("div1").className=s; } </script> <head> <style type="text/css"> .style1 { 100px; height: 100px; background-image:url('http://img.baidu.com/img/logo-zhidao.gif'); } .style2 { 100px; height: 100px; background-image:url('http://img.baidu.com/img/iknow/images/r1s1g5.gif'); } </style> </head> <BODY > <select onchange="setDivBG(this.value);"> <option value="style1">知道</option> <option value="style2">头像</option> </select> <div id="div1" class="style2" > </div> </BODY>