Reports

Just regex and no toLocaleString():

var table = document.querySelector('.my_table_280125');
var last_cell = table.querySelector('tr:last-of-type td:last-of-type');
var sum = 0;

for( var i = 0; i < table.rows.length - 1; i++ ){
    sum = sum + parseFloat( table.rows[ i ].cells[ 1 ].textContent );
}

last_cell.textContent = sum.toString().replace(/(\d)(?=(\d\d\d)+(?!\d))/g, '$1,');

<table cellpadding="20" cellspacing="0" width="100%" border="1" class="my_table_280125">
    <tr>
        <td>Number #1</td>
        <td align="right">1234</td>
    </tr>
    <tr>
        <td>Number #2</td>
        <td align="right">12345</td>
    </tr>
    <tr>
        <td>Number #3</td>
        <td align="right">123456</td>
    </tr>
    <tr>
        <td>Total:</td>
        <td align="right"></td>
    </tr>
</table>

From: http://www.kompx.com/en/add-thousands-separator-into-numbers-javascript.htm

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