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C # tutorial
Nodes can be navigated using node relationships
Accessing nodes in the node tree via the relationship between nodes, is often called "navigating nodes".
In the XML DOM, node relationships are defined as properties to the nodes:
The following image illustrates a part of the node tree and the relationship between nodes in books.xml:
All nodes have exactly one parent node. The following code navigates to the parent node of <book>:
function myFunction(xml) {
var xmlDoc = xml.responseXML;
var x = xmlDoc.getElementsByTagName("book")[0];
document.getElementById("demo").innerHTML = x.parentNode.nodeName;
}
Example explained:
Some browsers might treat empty white-spaces or new lines as text nodes. This causes a problem when using the properties: firstChild, lastChild, nextSibling, previousSibling.
To avoid navigating to empty text nodes (spaces and new-line characters between element nodes), we use a function that checks the node type:
function get_nextSibling(n)
{
var y = n.nextSibling;
while (y.nodeType != 1)
{
y = y.nextSibling;
}
return y;
}
The function above allows you to use get_nextSibling(node) instead of the property node.nextSibling.
Code explained:
Element nodes are type 1. If the sibling node is not an element node, it moves to the next nodes until an element node is found.
The following code displays the first element node of the first <book>:
<!DOCTYPE html>
<html>
<body>
<p id="demo"></p>
<script>
var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
if (this.readyState == 4 && this.status == 200) {
myFunction(this);
}
};
xhttp.open("GET",
"books.xml", true);
xhttp.send();
function myFunction(xml) {
var xmlDoc = xml.responseXML;
var x = get_firstChild(xmlDoc.getElementsByTagName("book")[0]);
document.getElementById("demo").innerHTML = x.nodeName;
}
//check if
the first node is an element node
function get_firstChild(n) {
var y = n.firstChild;
while (y.nodeType != 1) {
y = y.nextSibling;
}
return y;
}
</script>
</body>
</html>
Output:
title
Example explained: