jQuery取值

  <title>jquery取值</title>
    <script src="js/jquery-1.3.2.min.js"></script>
    <script type="text/javascript">
     $(function(){
        $("#btn_submit")
         .click(function(){
           var phone =$("#txt_UserPhone").val();
           var content=$("#txt_MessageContent").val();
           if(phone.length<9)
           {
              alert("请正确输入联系方式");
               return false;
           }
            if(content.length<0||content=="")
            {
              alert("请输入留言内容");
              return false;
            }
   
    });//click end
   
   });//end

    </script>