JSFiddle - React, Tailwind, and code Playground

HTML

<table>
<td id="tabela">
<input type="text" id="tabelainput" class="janmembros" maxlength="3" name="janmembros" value="2" 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>
    </table>
<BR><BR>
    <table>
<td id="tabela">
<input type="text" id="tabelainput" class="janmembros" maxlength="3" name="janmembros" value="3" disabled>
</td>
<td id="tabela">
<input type="text" id="tabelainput" class="janvisitantes" maxlength="3" name="janvisitantes" value="4" disabled>
</td>
<td id="tabela3" class="jantotal">3
</td>
    </table>
<BR><BR>
    <table>
<td id="tabela">
<input type="text" id="tabelainput" class="janmembros" maxlength="3" name="janmembros" value="5" 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>
    </table>

CSS

#tabela {
border: 0px;
margin: 0px;
position: relative;
height: 28px;
text-align: center;
width: 100px;
padding: 0px;
background-color: #f0f0f0;
color: #000;
float: left;
}



#tabela2 {
float: left;
border: 0px;
margin: 0px;
position: relative;
height: 22px;
text-align: center;
width: 100px;
padding: 0px;
background-color: #3b3b3b;
color: #FFF;
}

#tabela1 {
zoom: 90%;
float: left;
border: 0px;
margin-top: 0px;
background-color: #000;
font-size: 12px;
color: #ff0000;
text-align: center;
}

#tabelainput {
float: left;
border: 0px;
background-color: #f0f0f0;
color: #000;
height: 28px;
width: 100px;
text-align: center;
margin: 5px;
font-size: 16px;
}

#tabela3 {
float: left;
border: 0px;
margin: 0px;
height: 35px;
text-align: center;
width: 100px;
padding: 0px;
background-color: #4d51a8;
color: #FFF;
font-size: 18px;
line-height: 35px;
}

JavaScript

if ( $( ".janmembros" ).val().length >= 1 && $( ".janvisitantes" ).val().length >= 1 )
{
$( ".jantotal" ).html( parseInt($( ".janmembros" ).val()) + parseInt($( ".janvisitantes" ).val()) );
}