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<title>XML DOM - Node List and NamedNodeMap</title>
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<p>From <b>http://www.w3schools.com</b> (Copyright Refsnes Data)</p>
<h1>XML DOM Node List</h1>
<a href="dom_nodes_info.asp"><img border="0" src="../images/btn_previous.gif" alt="prev" width="100" height="20" /></a>
<a href="dom_nodes_traverse.asp"><img border="0" src="../images/btn_next.gif" alt="next" width="100" height="20" /></a>
<hr />
<p class="intro">A list of nodes is returned by the getElementsByTagName()
method and the childNodes property.</p>
<hr />
<h2>Examples
</h2>
<p>The examples below use the XML file
<a target="_blank" href="books.xml">books.xml</a>. <br />
A function, <a href="dom_loadxmldoc.asp">loadXMLDoc()</a>, in an external JavaScript is used to load the XML file.</p>
<p><a target="_blank" href="tryit.asp@filename=try_dom_nodelist">Get the text
from the first <title> element</a><br />
This example uses the getElementsByTagName() method to get the text from the
first <title> element in "books.xml".</p>
<p><a target="_blank" href="tryit.asp@filename=try_dom_nodelist_length">Loop through
nodes using the length property</a><br />
This example uses node list and the length property to loop through all <title>
elements in "books.xml"</p>
<p><a target="_blank" href="tryit.asp@filename=try_dom_attributes">Get the
attribute of an element</a><br />
This example uses a attribute list to get attribute from the first <book>
element in "books.xml".</p>
<hr />
<h2>DOM Node List</h2>
<p>When using properties or methods like childNodes or getElementsByTagName(),
a node list object is returned.</p>
<p>A node list object represents a list of nodes, in the same order as in the
XML.</p>
<p>Nodes in the node list are accessed with index numbers starting from 0.</p>
<p>The following image represents a node list of the <title> elements in "<a target="_blank" href="books.xml">books.xml</a>":</p>
<img border="0" src="nodelist.gif" alt="DOM node list" /><br />
<p>The following code fragment loads "<a target="_blank" href="books.xml">books.xml</a>"
into xmlDoc using <a href="dom_loadxmldoc.asp">loadXMLDoc()</a> and returns a node list of title elements in "books.xml":</p>
<table class="ex" id="table38" border="1" cellspacing="0" width="100%">
<tr>
<td>
<pre>xmlDoc=loadXMLDoc("books.xml");</pre>
<pre>x=xmlDoc.getElementsByTagName("title");</pre>
</td>
</tr>
</table>
<p>After the execution of the statement above, x is a node list object.</p>
<p>The following code fragment returns the text from the first <title> element
in the node list (x):</p>
<table class="ex" id="table40" border="1" cellspacing="0" width="100%">
<tr>
<td>
<pre>txt=x[0].childNodes[0].nodeValue;</pre>
</td>
</tr>
</table>
<p>After the execution of the statement above, txt = "Everyday Italian".</p>
<p><a target="_blank" href="tryit.asp@filename=try_dom_nodelist">Try it yourself.</a></p>
<hr />
<h2>Node List Length</h2>
<p>A node list object keeps itself up-to-date. If an element is
deleted or added, the list is automatically
updated.</p>
<p>The length property of a node list is
the number of nodes in the list.</p>
<p>The following code fragment loads "<a target="_blank" href="books.xml">books.xml</a>"
into xmlDoc using <a href="dom_loadxmldoc.asp">loadXMLDoc()</a> and returns the number of <title> elements in "books.xml":</p>
<table class="ex" id="table19" border="1" cellspacing="0" width="100%">
<tr>
<td>
<pre>xmlDoc=loadXMLDoc("books.xml");</pre>
<pre>x=xmlDoc.getElementsByTagName('title').length;</pre>
</td>
</tr>
</table>
<p>After the execution of the statement above, x = 4.</p>
<p>The length of the node list can be used to loop through all the elements in
the list.</p>
<p>The following code fragment uses the length property to loop through the list
of <title> elements:</p>
<table class="ex" id="table22" border="1" cellspacing="0" width="100%">
<tr>
<td>
<pre>xmlDoc=loadXMLDoc("books.xml");</pre>
<pre>//the x variable will hold a node list
x=xmlDoc.getElementsByTagName('title');</pre>
<pre>for (i=0;i<x.length;i++)
{
document.write(x[i].childNodes[0].nodeValue);
document.write("<br />");
}</pre>
</td>
</tr>
</table>
<p>Output:</p>
<table class="ex" id="table23" border="1" cellspacing="0" width="100%">
<tr>
<td>
<pre>Everyday Italian
Harry Potter
XQuery Kick Start
Learning XML</pre>
</td>
</tr>
</table>
<p>Example explained:</p>
<ol>
<li>Load "<a target="_blank" href="books.xml">books.xml</a>"
into xmlDoc using <a href="dom_loadxmldoc.asp">loadXMLDoc()</a> </li>
<li>Set the x variable to hold a node list of all title elements</li>
<li>Output the value from the text node of all <title> elements</li>
</ol>
<p><a target="_blank" href="tryit.asp@filename=try_dom_nodelist_length">Try it yourself.</a></p>
<hr />
<h2>DOM Attribute List (Named Node Map)</h2>
<p>The attributes property of an element node returns a list of attribute nodes.</p>
<p>This is called a named node map, and is similar to a node list, except for
some differences in methods and properties.</p>
<p>A attribute list keeps itself up-to-date. If an attribute is
deleted or added, the list is automatically
updated.</p>
<p>The following code fragment loads "<a target="_blank" href="books.xml">books.xml</a>"
into xmlDoc using <a href="dom_loadxmldoc.asp">loadXMLDoc()</a> and returns a list of attribute nodes from the first <book> element in "books.xml":</p>
<table class="ex" id="table43" border="1" cellspacing="0" width="100%">
<tr>
<td>
<pre>xmlDoc=loadXMLDoc("books.xml");</pre>
<pre>x=xmlDoc.getElementsByTagName('book')[0].attributes;</pre>
</td>
</tr>
</table>
<p>After the execution of the code above, x.length = is the number of attributes
and x.getNamedItem() can be used to return an attribute node.</p>
<p>The following code fragment displays the value of the "category"
attribute, and the number of attributes, of a book:</p>
<table class="ex" id="table44" border="1" cellspacing="0" width="100%">
<tr>
<td>
<pre>xmlDoc=loadXMLDoc("books.xml");</pre>
<pre>x=xmlDoc.getElementsByTagName("book")[0].attributes;</pre>
<pre>document.write(x.getNamedItem("category").nodeValue);
document.write("<br />" + x.length);</pre>
</td>
</tr>
</table>
<p>Output:</p>
<table class="ex" id="table45" border="1" cellspacing="0" width="100%">
<tr>
<td>
<pre>cooking
1</pre>
</td>
</tr>
</table>
<p>Example explained:</p>
<ol>
<li>Load "<a target="_blank" href="books.xml">books.xml</a>"
into xmlDoc using <a href="dom_loadxmldoc.asp">loadXMLDoc()</a> </li>
<li>Set the x variable to hold a list of all attributes of the first <book>
element</li>
<li>Output the value from the "category" attribute</li>
<li>Output the length of the attribute list</li>
</ol>
<p><a target="_blank" href="tryit.asp@filename=try_dom_attributes">Try it yourself.</a></p>
<hr />
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<p>From <b>http://www.w3schools.com</b> (Copyright Refsnes Data)</p>
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