Node

Node is an interface from which various types of DOM API objects inherit, allowing those types to be treated similarly; for example, inheriting the same set of methods, or being testable in the same way.

All of the following interfaces inherit the Node interface's methods and properties: Document, Element, Attr, CharacterData (which Text, Comment, and CDATASection inherit), ProcessingInstruction, DocumentFragment, DocumentType, Notation, Entity, EntityReference

Those interfaces may return null in certain cases where the methods and properties are not relevant. They may throw an exception — for example when adding children to a node type for which no children can exist.

Properties

Inherits properties from its parent, EventTarget.[1]

Node.baseURIRead only
Returns a DOMString representing the base URL of the document containing the Node.
Node.baseURIObject  Read only
(Not available to web content.) The nsIURI object representing the base URI for the element.
Node.childNodesRead only
Returns a live NodeList containing all the children of this node. NodeList being live means that if the children of the Node change, the NodeList object is automatically updated.
Node.firstChildRead only
Returns a Node representing the first direct child node of the node, or null if the node has no child.
Node.isConnectedRead only
A boolean indicating whether or not the Node is connected (directly or indirectly) to the context object, e.g. the Document object in the case of the normal DOM, or the ShadowRoot in the case of a shadow DOM.
Node.lastChildRead only
Returns a Node representing the last direct child node of the node, or null if the node has no child.
Node.nextSiblingRead only
Returns a Node representing the next node in the tree, or null if there isn't such node.
Node.nodeNameRead only
Returns a DOMString containing the name of the Node. The structure of the name will differ with the node type. E.g. An HTMLElement will contain the name of the corresponding tag, like 'audio' for an HTMLAudioElement, a Text node will have the '#text' string, or a Document node will have the '#document' string.
Node.nodeTypeRead only
Returns an unsigned short representing the type of the node. Possible values are:
Name Value
ELEMENT_NODE 1
ATTRIBUTE_NODE  2
TEXT_NODE 3
CDATA_SECTION_NODE 4
ENTITY_REFERENCE_NODE  5
ENTITY_NODE  6
PROCESSING_INSTRUCTION_NODE 7
COMMENT_NODE 8
DOCUMENT_NODE 9
DOCUMENT_TYPE_NODE 10
DOCUMENT_FRAGMENT_NODE 11
NOTATION_NODE  12
Node.nodeValue
Returns / Sets the value of the current node.
Node.ownerDocumentRead only
Returns the Document that this node belongs to. If the node is itself a document, returns null.
Node.parentNodeRead only
Returns a Node that is the parent of this node. If there is no such node, like if this node is the top of the tree or if doesn't participate in a tree, this property returns null.
Node.parentElementRead only
Returns an Element that is the parent of this node. If the node has no parent, or if that parent is not an Element, this property returns null.
Node.previousSiblingRead only
Returns a Node representing the previous node in the tree, or null if there isn't such node.
Node.textContent
Returns / Sets the textual content of an element and all its descendants.

Obsolete properties

Node.localName  Read only
Returns a DOMString representing the local part of the qualified name of an element.

Note: In Firefox 3.5 and earlier, the property upper-cases the local name for HTML elements (but not XHTML elements). In later versions, this does not happen, so the property is in lower case for both HTML and XHTML.

Node.namespaceURI  Read only
The namespace URI of this node, or null if it is no namespace.

Note: In Firefox 3.5 and earlier, HTML elements are in no namespace. In later versions, HTML elements are in the http://www.w3.org/1999/xhtml/ namespace in both HTML and XML trees.

Node.nodePrincipal  Obsolete since Gecko 46
A nsIPrincipal representing the node principal.
Node.prefix  Read only
Is a DOMString representing the namespace prefix of the node, or null if no prefix is specified.
Node.rootNode  Read only
Returns a Node object representing the topmost node in the tree, or the current node if it's the topmost node in the tree. This has been replaced by Node.getRootNode().

Methods

Inherits methods from its parent, EventTarget.[1]

Node.appendChild(childNode)
Adds the specified childNode argument as the last child to the current node.
If the argument referenced an existing node on the DOM tree, the node will be detached from its current position and attached at the new position.
Node.cloneNode()
Clone a Node, and optionally, all of its contents. By default, it clones the content of the node.
Node.compareDocumentPosition()
Compares the position of the current node against another node in any other document.
Node.contains()
Returns a Boolean value indicating whether or not a node is a descendant of the calling node.
Node.getBoxQuads()
Returns a list of the node's CSS boxes relative to another node.
Node.getRootNode()
Returns the context object's root which optionally includes the shadow root if it is available. 
Node.hasChildNodes()
Returns a Boolean indicating whether or not the element has any child nodes.
Node.insertBefore()
Inserts a Node before the reference node as a child of a specified parent node.
Node.isDefaultNamespace()
Accepts a namespace URI as an argument and returns a Boolean with a value of true if the namespace is the default namespace on the given node or false if not.
Node.isEqualNode()
Returns a Boolean which indicates whether or not two nodes are of the same type and all their defining data points match.
Node.isSameNode()
Returns a Boolean value indicating whether or not the two nodes are the same (that is, they reference the same object).
Node.lookupPrefix()
Returns a DOMString containing the prefix for a given namespace URI, if present, and null if not. When multiple prefixes are possible, the result is implementation-dependent.
Node.lookupNamespaceURI()
Accepts a prefix and returns the namespace URI associated with it on the given node if found (and null if not). Supplying null for the prefix will return the default namespace.
Node.normalize()
Clean up all the text nodes under this element (merge adjacent, remove empty).
Node.removeChild()
Removes a child node from the current element, which must be a child of the current node.
Node.replaceChild()
Replaces one child Node of the current one with the second one given in parameter.

Obsolete methods

Node.getFeature() 
Node.getUserData() 
Allows a user to get some DOMUserData from the node.
Node.hasAttributes() 
Returns a Boolean indicating if the element has any attributes, or not.
Node.isSupported() 
Returns a Boolean flag containing the result of a test whether the DOM implementation implements a specific feature and this feature is supported by the specific node.
Node.setUserData() 
Allows a user to attach, or remove, DOMUserData to the node.

Examples

Remove all children nested within a node

function removeAllChildren(element) {
  while (element.firstChild) {
    element.removeChild(element.firstChild)
  }
}

Sample usage

/* ... an alternative to document.body.innerHTML = "" ... */
removeAllChildren(document.body)

Recurse through child nodes

The following function recursively calls a callback function for each node contained by a root node (including the root itself):

function eachNode(rootNode, callback) {
	if (!callback) {
		const nodes = []
		eachNode(rootNode, function(node) {
			nodes.push(node)
		})
		return nodes
	}

	if (false === callback(rootNode)) {
		return false
    }

	if (rootNode.hasChildNodes()) {
		const nodes = rootNode.childNodes
		for (let i = 0, l = nodes.length; i < l; ++i) {
			if (false === eachNode(nodes[i], callback)) {
				return
            }
        }
	}
}

Syntax

eachNode(rootNode, callback)

Description

Recursively calls a function for each descendant node of rootNode (including the root itself).

If callback is omitted, the function returns an Array instead, which contains rootNode and all nodes contained within.

If callback is provided, and it returns Boolean false when called, the current recursion level is aborted, and the function resumes execution at the last parent's level. This can be used to abort loops once a node has been found (such as searching for a text node which contains a certain string).

Parameters

rootNode
The Node object whose descendants will be recursed through.
callback Optional
An optional callback function that receives a Node as its only argument. If omitted, eachNode returns an Array of every node contained within rootNode (including the root itself).

Sample usage

The following example prints the textContent properties of each <span> tag in a <div> element named "box":

<div id="box">
  <span>Foo</span>
  <span>Bar</span>
  <span>Baz</span>
</div>
const box = document.getElementById("box")
eachNode(box, function(node) {
  if (null != node.textContent) {
    console.log(node.textContent)
  }
})

The above will result in the following strings printing to the user's console:

"\n\t", "Foo", "\n\t", "Bar", "\n\t", "Baz"

Note: Whitespace forms part of a Text node, meaning indentation and newlines form separate Text between the Element nodes.

Realistic usage

The following demonstrates a real-world use of the eachNode() function: searching for text on a web-page.

We use a wrapper function named grep to do the searching:

function grep(parentNode, pattern) {
	const matches = []
	let endScan = false

	eachNode(parentNode, function(node){
		if (endScan) {
			return false
        }

		// Ignore anything which isn't a text node
		if (node.nodeType !== Node.TEXT_NODE) {
			return
        }

		if (typeof pattern === "string") {
			if (-1 !== node.textContent.indexOf(pattern)) {
				matches.push(node)
            }
		}
		else if (pattern.test(node.textContent)) {
			if (!pattern.global) {
				endScan = true
				matches = node
			}
			else {
                matches.push(node)
            }
		}
	})

	return matches
}

For example, to find Text nodes that contain typos:

const typos = ["teh", "adn", "btu", "adress", "youre", "msitakes"]
const pattern = new RegExp("\\b(" + typos.join("|") + ")\\b", "gi")
const mistakes = grep(document.body, pattern)
console.log(mistakes)

Specifications

Specification Status Comment
DOM
The definition of 'Node' in that specification.
Living Standard Added the following methods: getRootNode()
DOM4
The definition of 'Node' in that specification.
Obsolete Removed the following properties: attributes, namespaceURI, prefix, and localName.
Removed the following methods: isSupported(), hasAttributes(), getFeature(), setUserData(), and getUserData().
Document Object Model (DOM) Level 3 Core Specification
The definition of 'Node' in that specification.
Obsolete The methods insertBefore(), replaceChild(), removeChild(), and appendChild() returns one more kind of error (NOT_SUPPORTED_ERR) if called on a Document.
The normalize() method has been modified so that Text node can also be normalized if the proper DOMConfiguration flag is set.
Added the following methods: compareDocumentPosition(), isSameNode(), lookupPrefix(), isDefaultNamespace(), lookupNamespaceURI(), isEqualNode(), getFeature(), setUserData(), and getUserData().
Added the following properties: baseURI and textContent.
Document Object Model (DOM) Level 2 Core Specification
The definition of 'Node' in that specification.
Obsolete The ownerDocument property was slightly modified so that DocumentFragment also returns null.
Added the following properties: namespaceURI, prefix, and localName.
Added the following methods: normalize(), isSupported() and hasAttributes().
Document Object Model (DOM) Level 1 Specification
The definition of 'Node' in that specification.
Obsolete Initial definition.

Browser compatibility

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