Element.ariaPosInSet

The ariaPosInSet property of the Element interface reflects the value of the aria-posinset attribute, which defines an element's number or position in the current set of listitems or treeitems.

A DOMString containing an integer.

In this example the aria-posinset attribute on the element with an ID of article2 is set to "2". Using ariaPosInSet we update the value to "3".

<article id="article1" aria-posinset="1"> ... </article>
<article id="article2" aria-posinset="2"> ... </article>

let el = document.getElementById('article2');
console.log(el.ariaPosInSet); // "2"
el.ariaPosInSet = "3"
console.log(el.ariaPosInSet); // "3"