---
title: ElementInternals.ariaPosInSet
slug: Web/API/ElementInternals/ariaPosInSet
tags:
  - API
  - Property
  - Reference
  - ariaPosInSet
  - AriaAttributes
  - AriaMixin
  - ElementInternals
browser-compat: api.ElementInternals.ariaPosInSet
---
{{DefaultAPISidebar("DOM")}}

The **`ariaPosInSet`** property of the {{domxref("ElementInternals")}} 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.

> **Note:** Setting aria attributes on `ElementInternals` allows default semantics to be defined on a custom element. These may be overwritten by author-defined attributes, but ensure that default semantics are retained should the author delete those attributes, or fail to add them at all. For more information see the [Accessibility Object Model explainer](https://wicg.github.io/aom/explainer.html#default-semantics-for-custom-elements-via-the-elementinternals-object).

## Syntax

```js
let ariaPosInSet = ElementInternals.ariaPosInSet;
ElementInternals.ariaPosInSet = ariaPosInSet;
```

### Value

A {{domxref("DOMString")}} containing an integer.

## Examples

In this example the value of `ariaPosInSet` is set to "2".

```js
this.internals_.ariaPosInSet = "2";
```

## Specifications

{{Specifications}}

## Browser compatibility

{{Compat}}
