js 事件点击 显示 隐藏

<div style="position:absolute;left:40%;top:10%;border-style:dotted">
<img src="zgl.jpg"/><br/>
<center>
<input type="button" value="隐藏"/>
&nbsp;&nbsp;&nbsp;&nbsp;
<input type="button" value="显示"/>
</center>
</div>
<script type="text/javascript">
document.getElementsByTagName("input")[0].onclick=function(){
//将图像隐藏
var imgElement = document.images[0];
imgElement.style.visibility="hidden";
}
document.getElementsByTagName("input")[1].onclick=function(){
//将图像显示
var imgElement = document.images[0];
imgElement.style.visibility="visible";
}
document.getElementsByTagName("div")[0].onmouseover=function(){
//将图片放大
var imgElement = document.images[0];
//获取原来图片的大小
x = imgElement.width;
y = imgElement.height;
imgElement.width=imgElement.width*1.5;
imgElement.height=imgElement.height*1.5;
}
document.getElementsByTagName("div")[0].onmouseout=function(){
//将图片还原
var imgElement = document.images[0];
imgElement.width=x;
imgElement.height=y;
}
//全局变量
var x;
var y;
</script>