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15.3.1 Documents As Trees of Nodes

15.3.1 Documents As Trees of Nodes

The Document object, its Element objects, and the Text objects that represent runs of text in the document are all Node objects. Node defines the following important properties:


The Node that is the parent of this one, or null for nodes like the Document object

that have no parent.


A read-only array-like object (a NodeList) that is a live representation of a Node’s child nodes.

firstChild, lastChild

The first and last child nodes of a node, or null if the node has no children. nextSibling, previousSibling

The next and previous sibling node of a node. Two nodes with the same parent are

siblings. Their order reflects the order in which they appear in the document. These

properties connect nodes in a doubly linked list.

15.3 Document Structure and Traversal | 371


The kind of node this is. Document nodes have the value 9. Element nodes have the value 1. Text nodes have the value 3. Comments nodes are 8 and Document-Fragment nodes are 11.


The textual content of a Text or Comment node.


The tag name of an Element, converted to uppercase.

Using these Node properties, the second child node of the first child of the Document can be referred to with expressions like these:

document.childNodes[0].childNodes[1] document.firstChild.firstChild.nextSibling

Suppose the document in question is the following:

TestHello World!

Then the second child of the first child is theelement. It has a nodeType of 1 and a nodeName of “BODY”.

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