JSFiddle - React, Tailwind, and code Playground

HTML

<table cellspacing="0" rules="all" border="1" id="GridView1" 
       style="border-collapse:collapse;">
     <tr>
         <th scope="col">Col1</th>
         <th scope="col">Col2</th>
     </tr>
     <tr>
        <td>one</td>
        <td>two</td>
    </tr>
</table>

<div id="gridColumns"></div>

JavaScript

var table = document.getElementById('GridView1');
var headers = table.getElementsByTagName('th');

var div = document.getElementById("gridColumns");
for(var i=0;i<headers.length;i++)
{
    div.innerHTML += headers[i].innerText +"<br />";
}