This chapter explain you what a NodeList is, and what a NamedNodeMap is. It also explain the differences between them.

When using methods or properties like childNodes or getElementsByTagName(), we receive a NodeList object.

A NodeList object represent an ordered list of nodes.

The nodes in the NodeList can be accessed using their index number (starting from 0).

Note: In a NodeList, the nodes are returned in the order in which they are specified in the XML file.

Look at the XML file which is bookdetails.xml in  XML DOM Node page

We will now create a node list of all the <title> element in "bookdetails.xml", by using the getElementsByTagName("title") method. The following image represent the node list returned:

The node list always keeps itself up-to-date. If an element is added or deleted, in the node list or the XML document, the list is automatically updated.

The node list has a useful propertycalled length. The length property returns the number of node in a node list.

The following code fragment get the number of <title> elements in "bookdetails.xml":

When you know the length of node list, you can easily loop through it and extract the values you want.

The following code fragment loops through all <title> elements and print their values:

The NamedNodeMap always keeps itself up-to-date. If an element is added or deleted , in the node list or the XML document, the list is automatically updated.

The NamedNodeMap also has length property. The length property returns the number of nodes in list.

Look at the following XML file called bookdetails.xml in XML DOM Nodes page.

The following code fragment get the number of attributes in the first <title> element in "bookdetails.xml":

The getNamedItem() method of the NamedNodeMap object can be used to retrieve specified node.

The following code fragment shows how to print the value of the "category" attribute in each <book> element:

Last example will create a rectangle with rounded corner: