varuserAgent=navigator.userAgent.toLowerCase();varis_opera=userAgent.indexOf('opera')!=-1&&opera.version();varis_saf=userAgent.indexOf('applewebkit')!=-1||navigator.vendor=='AppleComputer,Inc.';varis_…

演示如下

 

 

div+css|div css|中国网站频道|心情走廊|设计|www.v404.cn

 

 

代码如下

 

<input type="text" value="请输入您的姓名" id="myinput" />
<script language="JavaScript" type="text/javascript">
   function addListener(element,e,fn){   
        if(element.addEventListener){   
             element.addEventListener(e,fn,false);   
         } else {   
             element.attachEvent("on" + e,fn);   
          }   
   }
   var myinput = document.getElementById("myinput");
   addListener(myinput,"click",function(){
    myinput.value = "";
   })
   addListener(myinput,"blur",function(){
    myinput.value = "请输入您的姓名";
   })
</script>
<a href="http://www.v404.cn/">div+css|div css|中国网站频道|心情走廊|设计|www.v404.cn</a>