JavaScript实现为input与textarea自定义hover,focus效果的方法

<title>JavaScript为input/textarea自定义hover,focus效果</title>
<script type="text/javascript">
function suckerfish(type, tag, parentId) { 
if (window.attachEvent) { 
window.attachEvent("onload", function() { 
var sfEls = (parentId==null)?document.getElementsByTagName(tag):document.getElementById(parentId).getElementsByTagName(tag); 
type(sfEls); 
}); 
} 
} 
sfHover = function(sfEls) { 
for (var i=0; i < sfEls.length; i++) { 
sfEls[i].onmouseover=function() { 
this.className+=" iptHover"; 
} 
sfEls[i].onmouseout=function() { 
this.className=this.className.replace(new RegExp(" iptHover\\b"), ""); 
} 
} 
} 
sfFocus = function(sfEls) { 
for (var i=0; i < sfEls.length; i++) { 
sfEls[i].onfocus=function() { 
this.className+=" iptFocus"; 
} 
sfEls[i].onblur=function() { 
this.className=this.className.replace(new RegExp(" iptFocus\\b"), ""); 
} 
} 
}
</script>
<style type="text/css">
textarea{
border:1px solid #BBE1F1;
width:250px;
height:80px;
}
 .iptHover,input:hover,textarea:hover{
border:1px solid #77C2E3;
}
.iptFocus,input:focus,textarea:focus{
border:1px solid #77C2E3;
background-color:#EFF7FF;
}
</style>
<input type="text" name="textfield" /><br />
<textarea name="textarea"></textarea>
<script type="text/javascript">
suckerfish(sfHover, "input");
suckerfish(sfFocus, "input");
suckerfish(sfHover, "textarea");
suckerfish(sfFocus, "textarea");
</script>