我創建了這樣的表單：問題是我無法獲得子總計字段的總計。我嘗試創建與總計總計相同的總計字段，但是沒有運氣。我想知道我是否犯了一個錯誤，即沒有在全局范圍內創建一些變量？有沒有簡單的解決方案可以做到這一點？您可以在這里找到完整的代碼：http : //autopartsdiscountcoupons.com/table/Form.html$("#con_qty116").bind('keyup mouseup', function() {  var rate = 40;  var qty = $("#con_qty116").val();  var val = qty * rate;  $("#con_qty116_td").text(val);  sub_total_of_weather_sheild();});$("#con_qty117").bind('keyup mouseup', function() {  var rate = 160;  var qty = $("#con_qty117").val();  var val = qty * rate;  $("#con_qty117_td").text(val);  sub_total_of_decorative_surface();});function sub_total_of_weather_sheild() {  var td116 = parseInt($("#con_qty116_td").text());  var sub_tot = td116;  $("#weather_sheild_qty_sub_total").text(sub_tot);  gr_total(sub_tot);}function sub_total_of_decorative_surface() {  var td117 = parseInt($("#con_qty117_td").text());  var sub_tot = td117;  $("#decorative_surface_qty_sub_total").text(sub_tot);}  <td>116</td>  <td>Provide and apply Weathershield (Reputable Brand) minimum...  </td>  <td>Sft</td>  <td><input id="con_qty116" name="con_qty116" type="number" /></td>  <td>40</td>  <td id="con_qty116_td">0</td>  <th colspan="4">Sub Total</th>  <td id="weather_sheild_qty_sub_total" colspan="2">0</td>  <td>117</td>  <td>Color Crete min 4mm thickness including surface preparation applied on prepared surface using Applicant Machine/Gun  </td>  <td>Sft</td>  <td><input id="con_qty117" name="con_qty117" type="number" /></td>  <td>160</td>  <td id="con_qty117_td">0</td></tr><tr>  <th colspan="4">Sub Total</th>  <td id="decorative_surface_qty_sub_total" colspan="2">0</td></tr><th colspan="4">Grand Total</th><th colspan="2" id="grand_total">0</th>