用style中的display属性。
<html>
<head></head>
<body>
<form>
<input type="button" name="a" style="display:''">
<Script Language="Javascript">
document.forms[0].a.style.display = none //Hide
//or document.forms[0].a.style.display = "" //Show
</Script>
</form>
</body>
</html>
<html>
<head></head>
<body>
<form>
<input type="button" name="a" style="display:''">
<Script Language="Javascript">
document.forms[0].a.style.display = none //Hide
//or document.forms[0].a.style.display = "" //Show
</Script>
</form>
</body>
</html>
<head></head>
<body>
<div id='mytext'>这是我的文字</div>
<br>
<a href=# onclick="javascript:document.all['mytext'].style.display=''">显示</a>
<a href=# onclick="javascript:document.all['mytext'].style.display='none'">隐藏</a>
</body>
</html>
<head>
<title>Untitled Document</title>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312">
<script language="javascript">
<!--
function Display(){
if(Tbl.style.display==""){
Tbl.style.display="none"
}
else
{
Tbl.style.display=""
}
}
//-->
</script>
</head><body bgcolor="#FFFFFF" text="#000000">
<div align="center">
<form name="form1" method="post" action="">
<table width="100%" border="0" cellspacing="0" cellpadding="0" id="Tbl">
<tr>
<td width="42%">
<div align="right">Your Message : </div>
</td>
<td width="58%">
<input type="text" name="Email" size="25">
</td>
</tr>
</table>
<input type="button" name="Show" value="Show" style="cursor:hand" onclick="javascript:Display()">
<input type="button" name="Hide" value="Hide" style="cursor:hand" onclick="javascript:Display()">
</form>
</div>
</body>
</html>