JavaScript: The Definitive Guide, 6th Edition

Name

NodeList — a read-only array-like object of Nodes

Synopsis

A NodeList is a read-only array-like object whose elements are Node objects (usually Elements). The length property specifies how many nodes are in the list, and you can retrieve those nodes from indexes 0 through length-1. You can also pass the desired index to the item() method instead of indexing the NodeList directly. The elements of a NodeList are always valid Node objects: NodeLists never contain null elements.

NodeLists are commonly used: the childNodes property of Node, and the return values of Document.getElementsByTagName(), Element.getElementsByTagName(), and HTMLDocument.get Elements ByName() are all NodeLists, for example. Because NodeList is an array-like object, however, we often refer to those values informally as arrays, using language like “the child Nodes[] array.”

Note that NodeList objects are usually live: they are not static snapshots but immediately reflect changes to the document tree. For example, if you have a NodeList that represents the children of a specific node and you then delete one of those children, the child is removed from your NodeList. Be careful when you are looping through the elements of a NodeList: the body of your loop can make changes to the document tree (such as deleting nodes) that can affect the contents of the NodeList!