[原]点击按钮，表格隔行变色：偶数行为黄色背景，奇数行为默认颜色。通过table的getElementsByTagName取得所有的tr，依次遍历，如果是偶数就…………。

window.onload = function () {

document.getElementById('btn').onclick = function () {

var trs = document.getElementById('tb').getElementsByTagName('tr');

for (var i = 0; i < trs.length; i++) {

if (i % 2 != 0) {

trs[i].style.backgroundColor = 'yellow';

} else {

trs[i].style.backgroundColor = '';

}

}

};

};

<input type="button" name="name" value="变色" id="btn" />

<table id="tb" border="1" cellpadding="0" cellspacing="0">

<tr>

<td>

AAAAAAAAAAAAAAAAAA

</td>

<td>

AAAAAAAAAAAAAAAAAA

</td>

<td>

AAAAAAAAAAAAAAAAAA

</td>

</tr>

<tr>

<td>

AAAAAAAAAAAAAAAAAA

</td>

<td>

AAAAAAAAAAAAAAAAAA

</td>

<td>

AAAAAAAAAAAAAAAAAA

</td>

</tr>

<tr>

<td>

AAAAAAAAAAAAAAAAAA

</td>

<td>

AAAAAAAAAAAAAAAAAA

</td>

<td>

AAAAAAAAAAAAAAAAAA

</td>

</tr>

<tr>

<td>

AAAAAAAAAAAAAAAAAA

</td>

<td>

AAAAAAAAAAAAAAAAAA

</td>

<td>

AAAAAAAAAAAAAAAAAA

</td>

</tr>

</table>