JavaScript: The Definitive Guide, 5th Edition

Name

NodeList: a read-only array of nodes — DOM Level 1 Core: Object → NodeList

Properties

readonly unsigned long length

The number of nodes in the array.

Methods

item()

Returns the specified element of the array.

Description

The NodeList interface defines a read-only, ordered list (i.e., an array) of Node objects. The length property specifies how many nodes are in the list, and the item( ) method allows you to obtain the node at a specified position in the list. The elements of a NodeList are always valid Node objects: NodeLists never contain null elements.

In JavaScript, NodeList objects behave like JavaScript arrays, and you can query an element from the list using square-bracket array notation instead of calling the item( ) method. However, you cannot assign new nodes to a NodeList using square brackets. Since it is always easier to think of a NodeList object as a read-only JavaScript array, this book uses the notation Element[] or Node[] (i.e., an Element array or Node array) instead of NodeList. The methods Document.getElementsByTagName( ), Element.getElementsByTagName( ), and HTMLDocument.getElementsByName( ) are all documented in this book as returning a Element[] instead of a NodeList object. Similarly, the childNodes property of the Node object is technically a NodeList object, but the Node reference page defines it as a Node[], and the property itself is usually referred to as “the childNodes[] array.”

Note that NodeList objects are live: they are not static snapshots but ...