為什么三個function都沒有效果
改變背景，添加一行和刪除，這三個function我的code都沒有working, 希望大家?guī)兔纯磫栴}在哪里，謝謝。
<!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(){
??????????????????
?????//?鼠標(biāo)移動改變背景,可以通過給每行綁定鼠標(biāo)移上事件和鼠標(biāo)移除事件來改變所在行背景色。
????????var?tr?=?document.getElementsByTagName(tr);?
for?(var?i=0;?i<tr.length;i++){
???? ?background(tr[i]);???
}
????????function?background(obj){
????????????obj.onmouseover?=?function(){
????????????????obj.style.backgroundColor?=?"#f2f2f2";
????????????}
????????????obj.onmouseout?=?function(){
????????????????obj.style.backgroundColor?=?"#fff";
????????????}????
????????????}
????????????
????????}
?????
?
?}
?????var?num?=?2
??????//?編寫一個函數(shù)，供添加按鈕調(diào)用，動態(tài)在表格的最后一行添加子節(jié)點；
?????function?add(){
?????????num?++;
?????????var?tr1?=?document.createElement("tr");
?????????var?td1?=?document.createElement("td");
?????????var?td2?=?document.createElement("td");
?????????var?td3?=?document.createElement("td");
?????????td1.innerHTML?=?"xh00"+num;
?????????td2.innerHTML?=?num;
?????????td3.innerHTML?=?"<a?href="javascript:;"?>刪除</a>";
?????????var?tr?=?document.getElementsByTagName("tr");
?????????tr.parentNode.lastChild.appendChild(tr1);
?????????tr1.appendChild(td1);
?????????tr1.appendChild(td2);
?????????tr1.appendChild(td3);
?????????
?????}
?????
?????function?delete(obj){
?????????var?tr?=?obj.parentNode.parentNode;
?????????tr.parentNode.removeChild(tr);
?????}
??? ?
?????//?創(chuàng)建刪除函數(shù)
?????
??</script>?
?</head>?
?<body>?
???<table?border="1"?width="50%"?id="table">
???<tr>
<th>學(xué)號</th>
<th>姓名</th>
<th>操作</th>
???</tr>??
???<tr>
<td>xh001</td>
<td>王小明</td>
<td><a?href="javascript:;"?onclick="delete(this);"?>刪除</a></td>???<!--在刪除按鈕上添加點擊事件??-->
???</tr>
???<tr>
<td>xh002</td>
<td>劉小芳</td>
<td><a?href="javascript:;"?onclick="delete(this);">刪除</a></td>???<!--在刪除按鈕上添加點擊事件??-->
???</tr>??
???</table>
???<input?type="button"?value="添加一行"?onclick="add()"?/>???<!--在添加按鈕上添加點擊事件??-->
?</body>
</html>
2015-08-29
<!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(){
???? // 鼠標(biāo)移動改變背景,可以通過給每行綁定鼠標(biāo)移上事件和鼠標(biāo)移除事件來改變所在行背景色。
??????? var tr = document.getElementsByTagName(tr);
??????? for (var i=0; i<tr.length;i++){
???????? background(tr[i]);??
??????? }
??????? function background(obj){
??????????? obj.onmouseover = function(){
??????????????? obj.style.backgroundColor = "#f2f2f2";
??????????? }
??????????? obj.onmouseout = function(){
??????????????? obj.style.backgroundColor = "#fff";
??????????? }???
????????? }??
??????? }
???? var num = 2//上面多了一個大括號
???? function add(){
???????? num ++;
???????? var tr1 = document.createElement("tr");
???????? var td1 = document.createElement("td");
???????? var td2 = document.createElement("td");
???????? var td3 = document.createElement("td");
???????? td1.innerHTML = "xh00"+num;
???????? td2.innerHTML = num;
???????? td3.innerHTML = "<a href=\"javascript:;\" onclick=\"del(this);\" >刪除</a>";//這行改了一下
???????? var table = document.getElementById("table");//這里改了
???????? table.lastChild.appendChild(tr1);//這里改了
???????? tr1.appendChild(td1);
???????? tr1.appendChild(td2);
???????? tr1.appendChild(td3);
???? }
???? function del(obj){ //這里用了關(guān)鍵字改成del
???????? var tr = obj.parentNode.parentNode;
???????? tr.parentNode.removeChild(tr);
???? }????
? </script>
?</head>
?<body>
?????? <table border="1" width="50%" id="table">
?????? <tr>
??????? <th>學(xué)號</th>
??????? <th>姓名</th>
??????? <th>操作</th>
?????? </tr>?
?
?????? <tr>
??????? <td>xh001</td>
??????? <td>王小明</td>
??????? <td><a href="javascript:;" onclick="del(this);" >刪除</a></td>?? <!--在刪除按鈕上添加點擊事件? -->
?????? </tr>
?
?????? <tr>
??????? <td>xh002</td>
??????? <td>劉小芳</td>
??????? <td><a href="javascript:;" onclick="del(this);">刪除</a></td>?? <!--在刪除按鈕上添加點擊事件? -->
?????? </tr>?
?
?????? </table>
?????? <input type="button" value="添加一行" onclick="add()" />?? <!--在添加按鈕上添加點擊事件? -->
?</body>
</html>