纯JS实现表格隔行变色与鼠标悬停高亮

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
#table {
width: 400px;
border-collapse: collapse;
}
</style>
</head>
<body>
<table id="table" border="1">
<thead>
<td>ID</td>
<td>姓名</td>
<td>年龄</td>
</thead>
<tbody>
<tr>
<td>1</td>
<td>黄艺</td>
<td>20</td>
</tr>
<tr>
<td>2</td>
<td>张三</td>
<td>21</td>
</tr>
<tr>
<td>3</td>
<td>李四</td>
<td>22</td>
</tr>
<tr>
<td>4</td>
<td>网无</td>
<td>23</td>
</tr>
</tbody>
</table>
</body>
<script type="text/javascript">
// 实现隔行变色，鼠标移入高亮
var table = document.getElementById("table");
var oldColor = "";//声明一个变量，保存表格原来的颜色
for(var i = 0; i < table.tBodies[0].rows.length; i++) {
//使用判断实现隔行变色
if(i % 2 == 0) {
table.tBodies[0].rows[i].style.backgroundColor = "gray";
} else {
table.tBodies[0].rows[i].style.backgroundColor = "#ccc";
}
//实现鼠标移入高亮
table.tBodies[0].rows[i].onmouseover = function() {
oldColor = this.style.backgroundColor;
this.style.backgroundColor = "red";
}
//实现鼠标移出变回原来的颜色
table.tBodies[0].rows[i].onmouseout = function() {
this.style.backgroundColor = oldColor;
}
}
</script>
</html>