JavaScript动态修改表格cellPadding与cellSpacing属性

<!DOCTYPE html>
<html>
<head>
<script>
function padding()
{
document.getElementById('myTable').cellPadding="15";
}
function spacing()
{
document.getElementById('myTable').cellSpacing="15";
}
</script>
</head>
<body>
<table id="myTable" border="1">
<tr>
<td>100</td>
<td>200</td>
</tr>
<tr>
<td>300</td>
<td>400</td>
</tr>
</table>
<br>
<input type="button" onclick="padding()"
value="Change Cellpadding">
<input type="button" onclick="spacing()"
value="Change Cellspacing">
</body>
</html>