sample: sum total for col in JavaScript

by sii_side

HTML

<table>
  <tr>
    <th></th>
    <th>A</th>
    <th>B</th>
  </tr>
  <tr>
    <td>あ</td>
    <td>4531</td>
    <td>7892</td>
  </tr>
  <tr>
    <td>い</td>
    <td>12</td>
    <td>789</td>
  </tr>
  <tr>
    <td>う</td>
    <td>8</td>
    <td>456</td>
  </tr>
  <tr>
    <td>え</td>
    <td>112</td>
    <td>100</td>
  </tr>
  <tr>
    <td>お</td>
    <td>80</td>
    <td>4</td>
  </tr>
  <tr>
    <td>か</td>
    <td>120</td>
    <td>79</td>
  </tr>
  <tr>
    <td>き</td>
    <td>36</td>
    <td>3</td>
  </tr>
</table>

CSS

th, td {
  border: 1px solid;
}

JavaScript

var total = 0;  //計算用の変数

var table = document.querySelector("table");
var tr    = table.rows;

for(var i = 1; i < tr.length; i++) {
	var cell = tr[i].cells[2];
  total += parseInt(cell.innerHTML);
}

window.alert("合計：" + total);