一个下拉框，想在submit按钮按下检查是否选择了内容

onclick="if(dvform.topicmode.value==''){alert('请选择!');return false;return true;"

解决方案 »

  1.   

    <html>
    <head>
            <script language="javascript">
            function check()
            {
                if(dvform.topicmode.value=="0")
                { 
                     alert("请选择");
                     return false;
                }      
                else
                     return true;    
            }
            </script>
            </head>
            <body>
                  <form name=dvform>
                        <select name=topicmode>
                              <option value="0">
                              <option value="1">aa
                              <option value="2">bb
                        </select>
                  <input type="submit" name=Submit  value="提交" onClick="check()">
           </form>
           </body>
    </html>