The ariaMultiLine property of the Element interface reflects the value of the aria-multiline attribute, which indicates whether a text box accepts multiple lines of input or only a single line.

A string with one of the following values:

"true"

This is a multi-line text box.

"false"

This is a single-line text box.

In this example the aria-multiline attribute on the element with an ID of txtBoxInput is set to "true" indicating that this box allows for multiple lines of input. Using ariaMultiLine we update the value to "false".

<div id="txtboxMultilineLabel">Enter the tags for the article</div>
<div
  role="textbox"
  id="txtBoxInput"
  contenteditable="true"
  aria-multiline="true"
  aria-labelledby="txtboxMultilineLabel"
  aria-required="true"></div>

let el = document.getElementById("txtBoxInput");
console.log(el.ariaMultiLine); // "true"
el.ariaMultiLine = "false";
console.log(el.ariaMultiLine); // "false"

• ARIA: textbox role