如何在javascript中求和表金额

Question

我有一个表，我现在给出了一些金额，我想合计表中的所有金额，我该怎么做？

我的代码：-

var tr = "";
var totalAmount = "";
var footerTr = "";
for(var i=1; i<=31; i++){
tr += `<tr>
<td>${i}</td>
<td>${i*2}</td>
</tr>`
totalAmount += `${i*2}+`
}
footerTr = `<tr>
<th>Total</th>
<th>${totalAmount}</th>
</tr>`
$('#saving_calc tbody').append(tr);
$('#saving_calc tfoot').append(footerTr);

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.1/dist/css/bootstrap.min.css">
<script src="https://cdn.jsdelivr.net/npm/jquery@3.6.0/dist/jquery.slim.min.js"></script>
<table class="table table-bordered"id="saving_calc" >
<thead>
<th>Date</th>
<th>Amount</th>
</thead>
<tbody>
</tbody>
<tfoot>
</tfoot>
</table>

谢谢你的努力！

Answer 1

像这样：

var tr = "";
var totalAmount = "";
var total = 0;  //this your total
var footerTr = "";
for(var i=1; i<=31; i++){
tr += `<tr>
<td>${i}</td>
<td>${i*2}</td>
</tr>`;
totalAmount += `${i*2}+`;
total += i*2;  //this your total
}
totalAmount = totalAmount.substring(0, totalAmount.length - 1); // remove last plus
totalAmount += '='+total;
footerTr = `<tr>
<th>Total</th>
<th>${totalAmount}</th>
</tr>`;
$('#saving_calc tbody').append(tr);
$('#saving_calc tfoot').append(footerTr);
console.log(total);//this your total

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap@4.6.1/dist/css/bootstrap.min.css">
<script src="https://cdn.jsdelivr.net/npm/jquery@3.6.0/dist/jquery.slim.min.js"></script>
<table class="table table-bordered"id="saving_calc" >
<thead>
<th>Date</th>
<th>Amount</th>
</thead>
<tbody>
</tbody>
<tfoot>
</tfoot>
</table>