Node

{{APIRef("DOM")}}

The {{Glossary("DOM")}} Node interface is an abstract base class upon which many other DOM API objects are based, thus letting those object types be used similarly and often interchangeably. As an abstract class, there is no such thing as a plain Node object. All objects that implement Node functionality are based on one of its subclasses. Most notable are {{domxref("Document")}}, {{domxref("Element")}}, and {{domxref("DocumentFragment")}}.

In addition, every kind of DOM node is represented by an interface based on Node. These include {{DOMxRef("Attr")}}, {{DOMxRef("CharacterData")}} (which {{DOMxRef("Text")}}, {{DOMxRef("Comment")}}, {{DOMxRef("CDATASection")}} and {{DOMxRef("ProcessingInstruction")}} are all based on), and {{DOMxRef("DocumentType")}}.

In some cases, a particular feature of the base Node interface may not apply to one of its child interfaces; in that case, the inheriting node may return null or throw an exception, depending on circumstances. For example, attempting to add children to a node type that cannot have children will throw an exception.

{{InheritanceDiagram}}

Instance properties

In addition to the properties below, Node inherits properties from its parent, {{DOMxRef("EventTarget")}}.

• {{DOMxRef("Node.baseURI")}} {{ReadOnlyInline}}

  • : Returns a string representing the base URL of the document containing the Node.

• {{DOMxRef("Node.childNodes")}} {{ReadOnlyInline}}

  • : Returns a live {{DOMxRef("NodeList")}} containing all the children of this node (including elements, text and comments). {{DOMxRef("NodeList")}} being live means that if the children of the Node change, the {{DOMxRef("NodeList")}} object is automatically updated.

• {{DOMxRef("Node.firstChild")}} {{ReadOnlyInline}}

  • : Returns a Node representing the first direct child node of the node, or null if the node has no child.

• {{DOMxRef("Node.isConnected")}} {{ReadOnlyInline}}

  • : A boolean indicating whether or not the Node is connected (directly or indirectly) to the context object, e.g., the {{DOMxRef("Document")}} object in the case of the normal DOM, or the {{DOMxRef("ShadowRoot")}} in the case of a shadow DOM.

• {{DOMxRef("Node.lastChild")}} {{ReadOnlyInline}}

  • : Returns a Node representing the last direct child node of the node, or null if the node has no child.

• {{DOMxRef("Node.nextSibling")}} {{ReadOnlyInline}}

  • : Returns a Node representing the next node in the tree, or null if there isn't such node.

• {{DOMxRef("Node.nodeName")}} {{ReadOnlyInline}}

  • : Returns a string containing the name of the Node. The structure of the name will differ with the node type. E.g. An {{DOMxRef("HTMLElement")}} will contain the name of the corresponding tag, like 'AUDIO' for an {{DOMxRef("HTMLAudioElement")}}, a {{DOMxRef("Text")}} node will have the '#text' string, or a {{DOMxRef("Document")}} node will have the '#document' string.

• {{DOMxRef("Node.nodeType")}} {{ReadOnlyInline}}

  • : 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
    PROCESSING_INSTRUCTION_NODE	7
    COMMENT_NODE	8
    DOCUMENT_NODE	9
    DOCUMENT_TYPE_NODE	10
    DOCUMENT_FRAGMENT_NODE	11

• {{DOMxRef("Node.nodeValue")}}

  • : Returns / Sets the value of the current node.

• {{DOMxRef("Node.ownerDocument")}} {{ReadOnlyInline}}

  • : Returns the {{DOMxRef("Document")}} that this node belongs to. If the node is itself a document, returns null.

• {{DOMxRef("Node.parentNode")}} {{ReadOnlyInline}}

  • : Returns a Node that is the parent of this node. If there is no such node — for example, if this node is the top of the tree, or if it doesn't participate in a tree — this property returns null.

• {{DOMxRef("Node.parentElement")}} {{ReadOnlyInline}}

  • : Returns an {{DOMxRef("Element")}} that is the parent of this node. If the node has no parent, or if that parent is not an {{DOMxRef("Element")}}, this property returns null.

• {{DOMxRef("Node.previousSibling")}} {{ReadOnlyInline}}

  • : Returns a Node representing the previous node in the tree, or null if there isn't such node.

• {{DOMxRef("Node.textContent")}}

  • : Returns / Sets the textual content of an element and all its descendants.

Instance methods

In addition to the methods below, Node inherits methods from its parent, {{DOMxRef("EventTarget")}}.

• {{DOMxRef("Node.appendChild()")}}
  • : 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.
• {{DOMxRef("Node.cloneNode()")}}
  • : Clone a Node, and optionally, all of its contents. By default, it clones the content of the node.
• {{DOMxRef("Node.compareDocumentPosition()")}}
  • : Compares the position of the current node against another node in any other document.
• {{DOMxRef("Node.contains()")}}
  • : Returns true or false value indicating whether or not a node is a descendant of the calling node.
• {{DOMxRef("Node.getRootNode()")}}
  • : Returns the context object's root which optionally includes the shadow root if it is available.
• {{DOMxRef("Node.hasChildNodes()")}}
  • : Returns a boolean value indicating whether or not the element has any child nodes.
• {{DOMxRef("Node.insertBefore()")}}
  • : Inserts a Node before the reference node as a child of a specified parent node.
• {{DOMxRef("Node.isDefaultNamespace()")}}
  • : Accepts a namespace URI as an argument and returns a boolean value with a value of true if the namespace is the default namespace on the given node or false if not.
• {{DOMxRef("Node.isEqualNode()")}}
  • : Returns a boolean value which indicates whether or not two nodes are of the same type and all their defining data points match.
• {{DOMxRef("Node.isSameNode()")}}
  • : Returns a boolean value indicating whether or not the two nodes are the same (that is, they reference the same object).
• {{DOMxRef("Node.lookupPrefix()")}}
  • : Returns a string containing the prefix for a given namespace URI, if present, and null if not. When multiple prefixes are possible, the result is implementation-dependent.
• {{DOMxRef("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.
• {{DOMxRef("Node.normalize()")}}
  • : Clean up all the text nodes under this element (merge adjacent, remove empty).
• {{DOMxRef("Node.removeChild()")}}
  • : Removes a child node from the current element, which must be a child of the current node.
• {{DOMxRef("Node.replaceChild()")}}
  • : Replaces one child Node of the current one with the second one given in parameter.

Events

• {{domxref("Node/selectstart_event", "selectstart")}}
  • : Fires when the user starts a new selection in this node.

Examples

Remove all children nested within a node

This function remove each first child of an element, until there are none left.

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

Using this function is a single call. Here we empty the body of the document:

removeAllChildren(document.body);

An alternative could be to set the textContent to the empty string: document.body.textContent = "".

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, (node) => {
      nodes.push(node);
    });
    return nodes;
  }

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

  if (rootNode.hasChildNodes()) {
    for (const node of rootNode.childNodes) {
      if (eachNode(node, callback) === false) {
        return;
      }
    }
  }
}

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

If callback is omitted, the function returns an {{jsxref("Array")}} instead, which contains rootNode and all nodes contained within.

If callback is provided, and it returns 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).

The function has two parameters:

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

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) {
  let matches = [];
  let endScan = false;

  eachNode(parentNode, (node) => {
    if (endScan) {
      return false;
    }

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

    if (typeof pattern === "string" && node.textContent.includes(pattern)) {
      matches.push(node);
    } else if (pattern.test(node.textContent)) {
      if (!pattern.global) {
        endScan = true;
        matches = node;
      } else {
        matches.push(node);
      }
    }
  });

  return matches;
}

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}