用button隐藏和显示 怎么实现不了 请指教
<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>style样式</title>
</head>
<body>
<h2 id="con">I love JavaScript</H2>
<p> JavaScript使网页显示动态效果并实现与用户交互功能。</p>
<script type="text/javascript">
var mychar=document.getElementById("con");
mychar.style.color="red";
mychar.style.backgroundColor="#CCC";
function yin(){
mychar.style.display="none";
}
function xianshi(){
mychar.style.display="block";
}
</script>
<form>
<input type="button" name="xianshi" value="xianshi" onclick="xianshi()"/>
<input type="button" name="yin" value="yin" onclick="yin()"/>
</form>
</body>
</html>
