自己写的TextWater

代码
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 4.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>告广浮漂</title>    
    <script type="text/javascript" src="jquery.js">    </script>
    <script type="text/javascript">    
    //上面引入 jQuery.js
    $.fn.textWaterMater = function(waterText){                    
            _span = $("<span style='color:red;border:1px solid blue;color:gray;font-size:0.8em;padding:4px;'></span>");
        
            _this = $(this);
            if(!waterText || waterText.length==0){
                waterText = $(this).val();
            }        
            _this.val("");
            _span.html(waterText);
            _span.height(_this.height());
            _span.width(_this.width());
            _this.before(_span).css({display:"none"});
            
            _span.click(function(){
                $(this).hide();
                _this.show();
                _this.focus();
            });    
            _this.blur(function(){
                if($(this).val().length==0){
                    _span.show();
                    $(this).hide();
                }
            });        
        
    };
    $(function(){    
        //整个文档中目前只能有一个 TextWater。
        //$("input:first").addClass($("input:last").attr("class"));
        //$("input:first").textWaterMater();
        //$("input:last").textWaterMater();
    });
    </script>
</head>
<body>    dsfdsaf
    <input type="text" value="请输入关键词进行搜索" />fdgfdsg
    <input type="text" value="请输入关键词进行搜索ddd" />fdgfdsg
    <input type="button" value="ddd"/>
</body>
</html>