JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tbody>
        <tr id="17" rel="17">
            <td><input type="text" value="SURNAME17, GIVENNAME17"></td>
            <td><input type="text" id="txtSIN17" value="123456789"></td>
        </tr>
        <!-- Here is the participant I'd like to get the SIN from -->
        <tr id="18" rel="18">
            <td><input type="text" value="SURNAME18, GIVENNAME18"></td>
                <td><input type="text" id="txtSIN18" value="487654321"></td>
        </tr>
    </tbody>
</table>

JavaScript

$(document).ready(function() {
    $('table tr').each(function (i, row) {
        var sinid = $(":last-child", this).val();
        console.log(sinid);
    });

});