JSFiddle - React, Tailwind, and code Playground
HTML
<div id="div">
<table>
<tr id="tr_id">
<td><input type=button value="Go" id="btn_id" /></td>
</tr>
</table>
</div>
JavaScript
$("#btn_id").click(function() {
//alert(btn_id.id);
alert($(this).attr("id"))
var btnId = $(this).attr("id");
//alert($(btnId).closest("tr").id);
alert($(this).closest("tr").attr("id"));
return false;
})