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:

<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.innerText += `\nparent's root: ${parent.getRootNode().nodeName}\n`; // #document
output.innerText += `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.innerText += `shadowChild.getRootNode() === shadowRoot : ${
  shadowChild.getRootNode() === shadowRoot
}\n`; // true
output.innerText += `shadowChild.getRootNode({ composed:false }) === shadowRoot : ${
  shadowChild.getRootNode({ composed: false }) === shadowRoot
}\n`; // true
output.innerText += `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

Browser compatibility