### 自定義屬性
~~~
<script>
var aBtn = document.getelebyname('input');
//aBtn[0].abc = 123;//abc即自定義屬性給aBtn加了一個屬性，也可以進行讀寫
for(var i = 0;i <aBtn.length;i++){
aBtn[i].abc = 123;
aBtn[i].xyz = true;
}
</script>
~~~
***
課堂練習-1：
鼠標點擊圖片發生變化，類似點擊桌面圖標
~~~
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
ul,li{padding:0;margin:0;list-style: none;}
li{width:70px;height:70px;float:left;background: url(img/notactive.png) no-repeat;margin-right:10px;}
</style>
<script type="text/javascript">
window.onload = function(){
var oUl = document.getElementById('list');
var aLi = oUl.getElementsByTagName('li');
for(var i = 0;i < aLi.length;i++){
// 自定義屬性-每個li身上自己有一個開關
aLi[i].onOff = true;
aLi[i].onclick = function(){
if(this.onOff){
this.style.background = 'url(img/active.png) no-repeat';
}else{
this.style.background = 'url(img/notactive.png) no-repeat';
}
this.onOff = !this.onOff;
}
}
}
</script>
</head>
<body>
<ul id="list">
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
</ul>
</body>
</html>
~~~
課堂練習-2
點擊按鈕實現圖片的切換
***
課堂作業-1：帶縮略圖的圖片切換
***
[圖片素材下載](https://pan.baidu.com/s/11Luvx0SiX71Zk01lpSUS_g)
