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Node: getRootNode() method

The getRootNode() method of the Node interface returns the context object's root, which optionally includes the shadow root if it is available.

Syntax

getRootNode()
getRootNode(options)

Parameters

options Optional

An object that sets options for getting the root node. The available options are:

composed: A boolean value that indicates whether the shadow root should be returned (false, the default), or a root node beyond shadow root (true).

Return value

An object inheriting from Node. This will differ in exact form depending on where you call getRootNode(); for example:

Calling it on an element inside a standard web page will return an HTMLDocument object representing the entire page (or <iframe>).
Calling it on an element inside a shadow DOM will return the associated ShadowRoot.
Calling it on an element that is not attached to a document or a shadow tree will return the root of the DOM tree it belongs to.

Examples

Example 1

The first simple example returns a reference to the HTML/document node:

const rootNode = node.getRootNode();

Example 2

This more complex example shows the difference between returning a normal root, and a root including the shadow root:

html

<div class="parent">
  <div class="child"></div>
</div>
<div class="shadowHost">shadowHost</div>
<pre id="output">Output: </pre>

const parent = document.querySelector(".parent");
const child = document.querySelector(".child");
const shadowHost = document.querySelector(".shadowHost");
const output = document.getElementById("output");

output.textContent += `\nparent's root: ${parent.getRootNode().nodeName} \n`; // #document
output.textContent += `child's  root: ${child.getRootNode().nodeName} \n\n`; // #document

// create a ShadowRoot
const shadowRoot = shadowHost.attachShadow({ mode: "open" });
shadowRoot.innerHTML =
  '<style>div{background:#2bb8aa;}</style><div class="shadowChild">shadowChild</div>';
const shadowChild = shadowRoot.querySelector(".shadowChild");

// The default value of composed is false
output.textContent += `shadowChild.getRootNode() === shadowRoot : ${
  shadowChild.getRootNode() === shadowRoot
} \n`; // true
output.textContent += `shadowChild.getRootNode({composed:false}) === shadowRoot : ${
  shadowChild.getRootNode({ composed: false }) === shadowRoot
} \n`; // true
output.textContent += `shadowChild.getRootNode({composed:true}).nodeName : ${
  shadowChild.getRootNode({ composed: true }).nodeName
} \n`; // #document

Example 3

This example returns the root of the unmounted tree. Note element here is the root of the tree (as it has no parent), so by definition its root is itself:

const element = document.createElement("p");
const child = document.createElement("span");

element.append(child);

const rootNode = child.getRootNode(); // <p><span></span></p>

element === rootNode; // true
element === element.getRootNode(); // true

Specifications

Specification
DOM Standard # ref-for-dom-node-getrootnode①

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`getRootNode`	54	79	53	No	41	10.1	54	54	53	41	10.3	6.0

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https://developer.mozilla.org/en-US/docs/Web/API/Node/getRootNode