表格表头为蓝色，表主体为白色，当鼠标放到表的非表头行时，这一行颜色变为黄色，鼠标离开时黄色消失。
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>鼠标经过表格变色</title>
<style>
table {
margin: 200px auto;
font-size: 12px;
border-collapse: collapse;
width: 500px;
height: 50px;
}
table thead tr {
font-size: 14px;
background-color: skyblue;
}
td {
border: 1px solid black;
}
.bgc{
background-color: yellow;
}
</style>
</head>
<body>
<table>
<thead>
<td>表头1</td>
<td>表头2</td>
<td>表头3</td>
</thead>
<tbody>
<tr>
<td>表格一行一列</td>
<td>表格一行二列</td>
<td>表格一行三列</td>
</tr>
<tr>
<td>表格二行一列</td>
<td>表格二行二列</td>
<td>表格二行三列</td>
</tr>
<tr>
<td>表格三行一列</td>
<td>表格三行二列</td>
<td>表格三行三列</td>
</tr>
<tr>
<td>表格四行一列</td>
<td>表格四行二列</td>
<td>表格四行三列</td>
</tr>
<tr>
<td>表格五行一列</td>
<td>表格五行二列</td>
<td>表格五行三列</td>
</tr>
</tbody>
</table>
<script>
var tr =document.querySelectorAll('tr');
for(var i = 0;i < tr.length ;i++){
tr[i].onmouseover = function(){
this.className = 'bgc';
}
tr[i].onmouseout = function(){
this.className = '';
}
}
</script>
</body>
</html>
