var tbody = document.getElementById('table').lastChild;
var trs = tbody.getElementsByTagName('tr');如上 target获取的是table下的最后一个子节点也就是最后一个<tr></tr>标签
那么为什么trs要在最后一个tr标签下获取tr标签呢？
源代码如下
<!DOCTYPE html>
<html>
<head>
<title> new document </title>
<meta http-equiv="Content-Type" content="text/html; charset=gbk"/>
<script type="text/javascript">
window.onload = function(){
var tbody = document.getElementById('table').lastChild;
var trs = tbody.getElementsByTagName('tr');
for(var i =1;i<trs.length;i++){
trs[i].onmouseover = function(){
this.style.backgroundColor ="#f2f2f2";
}
trs[i].onmouseout = function(){
this.style.backgroundColor ="#fff";
}
}
}
function addOne(obj){
var tbody = document.getElementById('table').lastChild;
var tr = document.createElement('tr');
var td = document.createElement("td");
td.innerHTML = "<input type='text'/>";
tr.appendChild(td);
td = document.createElement("td");
td.innerHTML = "<input type='text'/>";
tr.appendChild(td);
td = document.createElement("td");
td.innerHTML = "<a href='javascript:;' onclick='deleteRow(this)'>删除</a>";
tr.appendChild(td);
tbody.appendChild(tr);
}
function deleteRow(obj){
var tbody = document.getElementById('table').lastChild;
var tr = obj.parentNode.parentNode;
tbody.removeChild(tr);
}
</script>
</head>
<body>
<table border="1" width="50%" id="table">
<tr>
<th>学号</th>
<th>姓名</th>
<th>操作</th>
</tr>
<tr>
<td>xh001</td>
<td>王小</td>
<td><a href="javascript:;" onclick="deleteRow(this)">删除</a></td>
</tr>
<tr>
<td>xh002</td>
<td>刘小</td>
<td><a href="javascript:;" onclick="deleteRow(this)">删除</a></td>
</tr>
</table>
<input type="button" value="添加 onclick="addOne()" />
</body>
</html>table的子节点结构是text和tbody
var tbody = document.getElementById('table').lastChild; 这句话是获取tbody，所有tr和td都在tbody中