JavaScript实现文本框默认提示文字效果

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 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=utf-8" />
<title>js提示文字</title>
<style type="text/css">
input{
width:200px; height:24px;
line-height:24px; border:1px solid #999;
background:#ccc; margin:15px 0 0 100px;
padding:4px; color:#666;
}
.current{
background:#E0FEE4;
border:1px solid #093;
}
</style>
</head>
<body>
<input name="" type="text" value="请输入姓名："/><br />
<input name="" type="text" value="请输入昵称："/><br />
<input name="" type="text" value="输入验证码："/><br />
<input name="" type="text" value="请输入手机号码："/><br />
<input name="" type="text" value="请输入电子邮件："/>
<script type="text/javascript">
 var aInp=document.getElementsByTagName('input');
 var i=0;
 var sArray=[];
 for(i=0; i<aInp.length; i++)
 {
 aInp[i].index=i;
 sArray.push(aInp[i].value);
 aInp[i].onfocus=function()
 {
 if(sArray[this.index]==aInp[this.index].value)
 {
 aInp[this.index].value='';
 }
 aInp[this.index].className='current';
 };
 aInp[i].onblur=function()
 {
 if(aInp[this.index].value=='')
 {
 aInp[this.index].value=sArray[this.index];
 }
 aInp[this.index].className='';
 };
 }
</script>
</body>
</html>