aria-posinset attribute defines an element's number or position in the current set of listitems or treeitems when not all items are present in the DOM.
Short for "position in set", the
aria-posinset attribute defines the position of the element within the whole set of listitems or treeitems when only a subset of the items are present in the DOM.
If all the items in a list are present in the DOM, the browser can calculate the total and the position of each, making
aria-posinset unnecessary. When only a portion of a set is in the DOM, include
aria-posinset to provide information about the element's position within the set along with
aria-setsize to inform the user how many items are in the full set.
The following example shows a listbox with four element options out of the 118 in the periodic table of chemical elements.
<h2 id="periodic-table">Periodic table of chemical elements</h2> <ul role="listbox" aria-labelledby="periodic-table"> <li role="option" aria-setsize="118" aria-posinset="1">Hydrogen</li> <li role="option" aria-setsize="118" aria-posinset="3">Lithium</li> <li role="option" aria-setsize="118" aria-posinset="11">Sodium</li> <li role="option" aria-setsize="118" aria-posinset="19">Potassium</li> </ul>
The value of each
aria-posinset is an integer greater than or equal to
1, and less than or equal to the size of the set when that size is known.
Note: When using
aria-posinset you must also include value for
aria-setsize, which is the size of the entire set. If the size of the entire set is unknown, set
<article> element has
aria-posinset set to a value that represents its position in the feed along with the
aria-setsize set to either the number of articles that have been loaded or the total number in the feed, depending on which value is most helpful to users.
Integer greater than or equal to 1, and less than or equal to the value of
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