The ariaColSpan property of the Element interface reflects the value of the aria-colspan attribute, which defines the number of columns spanned by a cell or gridcell within a table, grid, or treegrid.

A string which contains an integer.

In this example the aria-colspan attribute on the element with an ID of spanning-heading is set to "2". Using ariaColSpan we update the value to "3".

<table>
  <tr>
    <th>Heading 1</th>
    <th>Heading 2</th>
    <th>Heading 3</td>
  </tr>
  <tr>
    <td colspan="2" aria-colspan="2" id="spanning-column">Spanning</td>
    <td>One</td>
  </tr>
</table>

let el = document.getElementById("spanning-column");
console.log(el.ariaColSpan);
el.ariaColSpan = "3";
console.log(el.ariaColSpan);

• ARIA: table role