JSFiddle - React, Tailwind, and code Playground

HTML

<div id="div1">
<table>
    <tr>
        <td id="tabela">
            <input type="text" id="tabelainput" class="janmembros" maxlength="3" name="janmembros" value="1" disabled>
        </td>
        <td id="tabela">
            <input type="text" id="tabelainput" class="janvisitantes" maxlength="3" name="janvisitantes" value="3" disabled>
        </td>
        <td id="tabela3" class="jantotal"></td>
    </tr>
</table>
<table>
    <tr>
        <td id="tabela">
            <input type="text" id="tabelainput" class="janmembros" maxlength="3" name="janmembros" value="15" disabled>
        </td>
        <td id="tabela">
            <input type="text" id="tabelainput" class="janvisitantes" maxlength="3" name="janvisitantes" value="2" disabled>
        </td>
        <td id="tabela3" class="jantotal"></td>
    </tr>
</table>
<table>
    <tr>
        <td id="tabela">
            <input type="text" id="tabelainput" class="janmembros" maxlength="3" name="janmembros" value="1" disabled>
        </td>
        <td id="tabela">
            <input type="text" id="tabelainput" class="janvisitantes" maxlength="3" name="janvisitantes" value="5" disabled>
        </td>
        <td id="tabela3" class="jantotal"></td>
    </tr>
</table>
<table>
    <tr>
        <td id="tabela"></td>
        <td id="tabela"></td>
        <td id="tabela3" class="total"></td>
    </tr>
</table>
</div>
    
<div id="div2">
<table>
    <tr>
        <td id="tabela">
            <input type="text" id="tabelainput" class="janmembros" maxlength="3" name="janmembros" value="1" disabled>
        </td>
        <td id="tabela">
            <input type="text" id="tabelainput" class="janvisitantes" maxlength="3" name="janvisitantes" value="8" disabled>
        </td>
        <td id="tabela3" class="jantotal"></td>
    </tr>
</table>
<table>
    <tr>
        <td id="tabela">
            <input type="text" id="tabelainput" class="janmembros" maxlength="3" name="janmembros" value="11" disabled>
        </td>
        <td...

CSS

#div1 {
    background-color: #deaaaa;
}

#div2 {
    background-color: #fdfdc1;
}

JavaScript

$('div').each(function() {
    var somatorio = 0;
    $('table', this).each(function (i) {
        var $this = $(this),
            janmembros = parseInt($this.find('.janmembros').val() || '0', 10),
            janvisitantes = parseInt($this.find('.janvisitantes').val() || '0', 10);
        $this.find('.jantotal').html(janmembros + janvisitantes);
        somatorio += parseInt($this.find( ".jantotal" ).html() || '0', 10);
    });
    $('.total', this).html(somatorio);
});