- 使用querySelectorAll获取元素集并计算总和
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>016</title>
</head>
<body>
<table id="table1">
<tr>
<td>Washington</td>
<td>145</td>
</tr>
<tr>
<td>Oregon</td>
<td>233</td>
</tr>
<tr>
<td>Missouri</td>
<td>833</td>
</tr>
</table>
</body>
<script type="text/javascript">
var sum = 0;
var cells = document.querySelectorAll("td + td");
for(var i = 0;i < cells.length; i++){
sum+=parseFloat(cells[i].firstChild.data);
}
var newRow = document.createElement("tr");
var firstCell = document.createElement("td");
var firstCellText = document.createTextNode("Sum:");
firstCell.appendChild(firstCellText);
var secondCell = document.createElement("td");
var secondCellText = document.createTextNode(sum);
secondCell.appendChild(secondCellText);
newRow.appendChild(firstCell);
newRow.appendChild(secondCell);
document.getElementById('table1').appendChild(newRow);
</script>
</html>
