如果不在jquery中使用每个循环，如何旋转值

Question

在学生标记列表中，我自动更改了标记1总数和平均值将发生变化 我在jquery

中使用了这样的代码

$("#total_" + this.name)[0].innerHTML = parseFloat($("#marks1_" + this.name).val()) + parseFloat($("#marks2_" + this.name).val()) + parseFloat($("#marks3_" + this.name).val());
$("#average_" + this.name)[0].innerHTML = (((parseFloat($("#marks1_" + this.name).val()) + parseFloat($("#marks2_" + this.name).val()) + parseFloat($("#marks3_" + this.name).val())) / 300) * 100).toFixed(2);

像这样如何在不使用每个循环的情况下自动更改总计 我像这样使用了总计

$("#grandtotal")[0].innerHTML += parseFloat($("#marks1_" + this.name).val()) + parseFloat($("#marks2_" + this.name).val()) + parseFloat($("#marks3_" + this.name).val());

Answer 1

在设置新学生总值之前，请获取旧值：

var oldStudentTotal = parseFloat($("#total_" + this.name).html());
var newStudentTotal = parseFloat($("#marks1_" + this.name).val()) + 
  parseFloat($("#marks2_" + this.name).val()) + 
  parseFloat($("#marks3_" + this.name).val());

$("#total_" + this.name).html(newStudentTotal);

然后，从旧总计中减去旧学生总值并添加新学生总值：

var oldGrandTotal = parseFloat($("#grandtotal").html());
var newGrandTotal = oldGrandTotal - oldStudentTotal + newStudentTotal;

$("#grandtotal").html(newGrandTotal);

对平均值做同样的事情。

Answer 2

拯救的递归！

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function rowRec($currentRow) {
  if ($currentRow.length == 0)
    return 0;

  var rowTotal = cellRec($currentRow.find(".mark").first());

  $currentRow.find(".total").text(rowTotal);
  $currentRow.find(".average").text(rowTotal / $currentRow.find(".mark").length);

  return rowTotal + rowRec($currentRow.next(".resultsRow"));
}

function cellRec($currentCell) {
  if ($currentCell.length == 0)
    return 0;
  var thisCellValue = parseFloat($currentCell.text());

  return thisCellValue + cellRec($currentCell.next(".mark"));
}

var grandTotal = rowRec($("tr.resultsRow").first());
var grandAvg = grandTotal / ($(".mark").length);
$(".grand_total").text(grandTotal);
$(".grand_average").text(grandAvg);

＆＃13;

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<table>
  <thead>
    <tr>
      <th>Name</th>
      <th>Age</th>
      <th>Mark1</th>
      <th>Mark2</th>
      <th>Mark3</th>
      <th>Total</th>
      <th>Average</th>
    </tr>
  </thead>
  <tbody>
    <tr class="resultsRow">
      <td class="name">Name 1</td>
      <td class="age">14</td>
      <td class="mark">75</td>
      <td class="mark">77</td>
      <td class="mark">84</td>
      <td class="total"></td>
      <td class="average"></td>
    </tr>
    <tr class="resultsRow">
      <td class="name">Name 2</td>
      <td class="age">17</td>
      <td class="mark">43</td>
      <td class="mark">56</td>
      <td class="mark">32</td>
      <td class="total"></td>
      <td class="average"></td>
    </tr>
    <tr class="resultsRow">
      <td class="name">Name 3</td>
      <td class="age">16</td>
      <td class="mark">87</td>
      <td class="mark">99</td>
      <td class="mark">75</td>
      <td class="total"></td>
      <td class="average"></td>
    </tr>
    <tr class="resultsRow">
      <td class="name">Name 4</td>
      <td class="age">15</td>
      <td class="mark">54</td>
      <td class="mark">67</td>
      <td class="mark">23</td>
      <td class="total"></td>
      <td class="average"></td>
    </tr>
  </tbody>
  <tfoot>
    <tr>
      <td></td>
      <td></td>
      <td></td>
      <td></td>
      <td></td>
      <td class="grand_total"></td>
      <td class="grand_average"></td>
    </tr>
  </tfoot>
</table>

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