JavaScript为input/textarea自定义hover,focus效果

<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;
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>