JavaScript Element ariaMultiLine Property

What You’ll Learn

Element.ariaMultiLine is an instance property that reflects the aria-multiline attribute. Learn the true and false tokens, when to prefer native <textarea> / <input>, and how to get or set the property from JavaScript—with five examples and try-it labs.

Introduction

Single-line fields and multi-line editors behave differently: Enter may submit a form, or it may insert a new line. Assistive technologies need to know which kind of text box they are in.

aria-multiline carries that signal. ariaMultiLine is the JavaScript reflection of that attribute.

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

Understanding the Property

MDN: 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.

• Reflected attribute — mirrors aria-multiline.
• Get / set — readable and writable string.
• Two tokens — true, false.
• Baseline — widely available since October 2023 (MDN).

📝 Syntax

ariaMultiLine

Value

A string with one of the following values:

📋 MDN Example Shape

MDN starts with a contenteditable textbox marked aria-multiline="true", then updates it 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"

Examples Gallery

Examples follow MDN Element: ariaMultiLine. Labs use a custom textbox so you can safely read and write the property.

const el = document.getElementById("txtBoxInput");
console.log(el.ariaMultiLine);

// HTML includes: role="textbox" aria-multiline="true"

true

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

true
false

const box = document.createElement("div");
box.setAttribute("role", "textbox");
box.setAttribute("contenteditable", "true");
box.setAttribute("aria-label", "Notes");
document.body.appendChild(box);

box.ariaMultiLine = "true";
console.log({
  ariaMultiLine: box.ariaMultiLine,
  attr: box.getAttribute("aria-multiline")
});

{
  "ariaMultiLine": "true",
  "attr": "true"
}

const el = document.createElement("div");
el.setAttribute("role", "textbox");
el.setAttribute("contenteditable", "true");
el.setAttribute("aria-multiline", "true");
el.setAttribute("aria-label", "Tags");
document.body.appendChild(el);

el.ariaMultiLine = "false";
console.log({
  fromProperty: el.ariaMultiLine,
  fromAttribute: el.getAttribute("aria-multiline"),
  same: el.ariaMultiLine === el.getAttribute("aria-multiline")
});

{
  "fromProperty": "false",
  "fromAttribute": "false",
  "same": true
}

console.log({
  supported: "ariaMultiLine" in Element.prototype,
  allowed: ["true", "false"],
  tip: "Prefer textarea / input when possible (MDN)",
  status: "Baseline Widely available (MDN)"
});

{
  "supported": true,
  "allowed": ["true", "false"],
  "tip": "Prefer textarea / input when possible (MDN)",
  "status": "Baseline Widely available (MDN)"
}

🚀 Common Use Cases

• Custom rich-text or tag editors built with contenteditable.
• Switching a custom field between single-line and multi-line modes.
• Design-system textboxes that cannot use native <textarea>.
• Keeping Enter-key behavior aligned with the announced textbox type.
• Keeping script and markup aligned without manual setAttribute.

🔧 How It Works

📝 Notes

• Not Deprecated, Experimental, or Non-standard on MDN (Baseline Widely available).
• Prefer native <input type="text"> or <textarea> when possible (MDN).
• Keep keyboard behavior aligned with the true / false value.
• Related: ariaMultiSelectable, ariaLabel, EventTarget, JavaScript hub.

💡 Best Practices