jquery sum column if row checked - php

Question

I have this table into a modal form:
<div class="form-group">
<!-- Record list -->
<table id="tabscarichi" class="table table-bordered table-striped" style='border-collapse: collapse;' >
<tr style='background: whitesmoke;'>
<th>Check</th>
<th>Id</th>
<th>Formulario</th>
<th>EER</th>
<th>Data FR</th>
<th>Q.tà</th>
</tr>
<?php
$query = "SELECT * FROM registro_c_s where stato_carico='1'";
$result = mysqli_query($conn,$query);
while($row = mysqli_fetch_array($result) ){
$id = $row['id'];
$fr = $row['formulario'];
$data = $row['data_fr'];
$eer = $row['codice_eer'];
$qta = $row['quantità'];
$stato = $row['stato_carico'];
?>
<tr>
<!-- Checkbox -->
<td><input type='checkbox' class="box" name='update[]' value='<?= $id ?>' ></td>
<td><?= $id ?></td>
<td><?= $fr ?></td>
<td><?= $eer ?></td>
<td><?= $data ?></td>
<td class="qta_scarichi"><?= $qta ?></td>
</tr>
<?php
}
?>
</table>
</div>
I'm trying to write a script to sum values of class .qta_scarichi and reporting it in another input number with .qtas class.
I tried this:
$('.box').change(function(){
var total = 0;
$('.box:checked').each(function(){
total+=parseFloat($(this).parent().next('td').find('.qta_scarichi').text());
});
$('#qtà').val(total);
});
But when i check some rows..nothing happen.. #qtà is the id of the input number that i want to fill..

Answer 1

Problem found! in table with id="tabscarichi" i have the following script:
$(function() {
$('#tabscarichi').hide();
$('#tipo').change(function(){
if($('#tipo').val() == 'scarico') {
$('#tabscarichi').show();
console.log('0'); }
else { $('#tabscarichi').hide();
} }); }); </script> ```
i choose to show the table with a select... if i disable the script.. the css selector works! But i don't understand why..

Answer 2

$(this).parent().next('td') just selects <td><?= $id ?></td>, which doesn't contain .qta_scarichi.
Use $(this).closest('tr').find('.qta_scarichi').
I suspect you may have intended ".siblings('td'). .next()` only selects the immediately following element.