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="1" 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="1" disabled>
        </td>
        <td...

CSS

#div1 {
    background-color: #deaaaa;
}

#div2 {
    background-color: #fdfdc1;
}

JavaScript

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