JSFiddle - React, Tailwind, and code Playground

HTML

<table border="1">
    <tr>
        <td>col1</td>
    </tr>
    <tr>
        <td>col2</td>
    </tr>
    <tr>
        <td>col3</td>
    </tr>
</table>

JavaScript

var table = document.getElementsByTagName('table')[0],
    rows = table.getElementsByTagName('tr'),
    text = 'textContent' in document ? 'textContent' : 'innerText';
console.log(text);

for (var i = 0, len = rows.length; i < len; i++){
    rows[i].children[0][text] = i + ': ' + rows[i].children[0][text];
}