JavaScript实现输入框获取与失去焦点时的样式切换

<!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=gb2312" /> 
<title>边框变色</title> 
<style type="text/css"> 
<!-- 
.SearchKeyword {border:1px solid #797A75;width: 202px;color: #CDCDCD;font-size:12px;} 
.SearchKeywordonFocus {border:1px solid #ABCD3A;width: 202px;color: #000000;font-size:12px;} 
--> 
</style> 
<script language="javascript"> 
function keywordfocus() 
{ 
if (document.formSearch.keyword.value == '请输入关键字') 
{ 
document.formSearch.keyword.value = ''; 
document.formSearch.keyword.className = 'SearchKeywordonFocus'; 
} 
} 
function keywordblur() 
{ 
if (document.formSearch.keyword.value == '') 
{ 
document.formSearch.keyword.value = '请输入关键字'; 
document.formSearch.keyword.className = 'SearchKeyword'; 
} 
} 
</SCRIPT> 
</head> 
<body> 
<form id="formSearch" name="formSearch" method="post" action=""> 
<input type="text" name="keyword" class="SearchKeyword" value="请输入关键字" onFocus="keywordfocus();" onBlur="keywordblur();" /> 
</form> 
</body> 
</html>