代码很简单,只用一行就可以,通过selectedIndex>-1返回false和true
<h3>判断eee是否存在sselect中</h3> <form method="post" name="f1" action=""> <select name="s1"> <option value="aaa">aaa</option> <option value="bbb">bbb</option> <option value="ccc">ccc</option> </select> </form> <script type="text/javascript"> <!-- var ss="eee"; f1.s1.value=ss; alert(f1.s1.selectedIndex>-1) // --> </script>