这是因为您使用的是childNodes，并且 DOM 中的空格被 Firefox 等视为文本节点。 al 但不是 IE
请参阅this answer 了解说明
我的建议
1.设置一些忽略除 1 (ELEMENT_NODE) 之外的任何 nodeType 的包装函数来进行 DOM 遍历。类似的东西
function child(elem, index) {
// if index is not supplied, default is 1
// you might be more comfortable making this 0-based
// in which case change i initial assignment value to 0 too
index = index || 1;
// get first child element node of elem
elem = (elem.firstChild && elem.firstChild.nodeType != 1) ?
next(elem.firstChild) :
elem.firstChild;
// use the index to move to nth-child element node
for(var i=1; i < index;i++) {
(function() {
return elem = next(elem);
})();
}
return elem;
}
function next(elem) {
do {
elem = elem.nextSibling;
} while (elem && elem.nodeType != 1);
return elem;
}
并像这样使用 - Working Demo - （答案底部的代码供参考）
<table id="myTable">
<thead>
...
</thead>
<tbody>
...
</tbody>
</table>
<script type="text/javascript">
child(document.getElementById('myTable'), 2); // will get the tbody
</script>
2.使用getElementbyId()、getElementsByTagName()或getElementsByName()而不是依赖于DOM中的位置
3.使用抽象出浏览器差异的 JavaScript 库（强烈推荐jQuery）
演示代码
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<script type="text/javascript">
window.onload = function() {
document.getElementById('getCellContents').onclick = getCellContents;
}
function child(elem, index) {
index = index || 1;
elem = (elem.firstChild && elem.firstChild.nodeType != 1) ?
next(elem.firstChild) :
elem.firstChild;
for(var i=1; i < index;i++) {
(function() {
return elem = next(elem);
})();
}
return elem;
}
function next(elem) {
do {
elem = elem.nextSibling;
} while (elem && elem.nodeType != 1);
return elem;
}
function getCellContents() {
var row = parseInt(document.getElementById('row').value, 10);
var column = parseInt(document.getElementById('column').value, 10);
var result;
var color;
var table = document.getElementById('table');
var cells = table.getElementsByTagName('td');
for (var i= 0; i < cells.length; i++) {
(function() {
cells[i].bgColor = '#ffffff';
})();
}
if (row && column) {
var tbody = child(table , 2);
var selectedRow = (row <= tbody.getElementsByTagName("tr").length)? child(tbody, row): null;
var selectedCell = (selectedRow && column <= selectedRow.getElementsByTagName("td").length)? child(selectedRow, column): null;
if (selectedRow && selectedCell) {
selectedCell.bgColor = '#00ff00';
result = selectedCell.innerHTML;
color = '#b7b7b7';
}
else {
result = 'Cell does not exist';
color = '#ff0000';
}
}
else {
result = 'You must provide numeric arguments for Row and Column Number';
color = '#ff0000';
}
var results = document.getElementById('results');
results.innerHTML = result;
results.style.color = color;
}
</script>
<title>DOM Traversal</title>
<meta http-equiv="Content-type" content="text/html; charset=utf-8" />
<style type="text/css">
body {
font-family: Verdana, Helvetica, Arial;
font-size: 0.8em;
}
h2 {
text-align:center;
}
table {
border: 1px solid #000;
border-collapse: collapse;
}
th, td {
border: 1px solid #000;
padding: 2px;
}
fieldset {
border: 0;
}
label {
display: block;
width: 120px;
text-align: right;
float: left;
padding-right: 10px;
margin: 5px 0;
}
input {
margin: 5px 0;
}
input.text {
padding: 0 0 0 3px;
width: 172px;
}
input.button {
margin: 15px 0 0 130px;
}
span {
font-weight: bold;
color: #b7b7b7;
}
</style>
</head>
<body>
<h2>Example to demonstrate use of JavaScript DOM traversing wrapper functions</h2>
<div style="margin: 0 auto; width: 600px;">
<fieldset>
<label for="row">Row Number:</label><input id="row" class="text" type="text" /><br/>
<label for="column">Column Number:</label><input id="column" class="text" type="text" /><br/>
<input id="getCellContents" type="button" class="button" value="Get Cell Contents" />
</fieldset>
<p>Results: <span id="results"></span></p>
<table id="table">
<thead>
<tr>
<th>Column 1</th>
<th>Column 2</th>
<th>Column 3</th>
<th>Column 4</th>
<th>Column 5</th>
</tr>
</thead>
<tbody>
<tr>
<td>Banana</td>
<td>Apple</td>
<td>Orange</td>
<td>Pineapple</td>
<td>Cranberry</td>
</tr>
<tr>
<td>Monkey</td>
<td>Giraffe</td>
<td>Elephant</td>
<td>Tiger</td>
<td>Snake</td>
</tr>
<tr>
<td>C#</td>
<td>Java</td>
<td>Python</td>
<td>Ruby</td>
<td>Haskell</td>
</tr>
<tr>
<td>France</td>
<td>Spain</td>
<td>Italy</td>
<td>Germany</td>
<td>Netherlands</td>
</tr>
</tbody>
</table>
<p style="font-weight:bold;">The Code:
<pre><code>
<script type="text/javascript">
window.onload = function() {
document.getElementById('getCellContents').onclick = getCellContents;
}
function child(elem, index) {
index = index || 1;
elem = (elem.firstChild && elem.firstChild.nodeType != 1) ?
next(elem.firstChild) :
elem.firstChild;
for(var i=1; i < index;i++) {
(function() {
if(elem)
return elem = next(elem);
})();
}
return elem;
}
function next(elem) {
do {
elem = elem.nextSibling;
} while (elem && elem.nodeType != 1);
return elem;
}
function getCellContents() {
var row = parseInt(document.getElementById('row').value, 10);
var column = parseInt(document.getElementById('column').value, 10);
var result;
var color;
var table = document.getElementById('table');
var cells = table.getElementsByTagName('td');
for (var i= 0; i < cells.length; i++) {
(function() {
cells[i].bgColor = '#ffffff';
})();
}
if (row && column) {
var tbody = child(table , 2);
var selectedRow = (row <= tbody.getElementsByTagName("tr").length)?
child(tbody, row): null;
var selectedCell = (selectedRow && column <= selectedRow.getElementsByTagName("td").length)?
child(selectedRow, column): null;
if (selectedRow && selectedCell) {
selectedCell.bgColor = '#00ff00';
result = selectedCell.innerHTML;
color = '#b7b7b7';
}
else {
result = 'Cell does not exist';
color = '#ff0000';
}
}
else {
result = 'You must provide numeric arguments for Row and Column Number';
color = '#ff0000';
}
var results = document.getElementById('results');
results.innerHTML = result;
results.style.color = color;
}
</script>
</code>
</pre>
</p>
</div>
</body>
</html>