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>