XML DOM - Accessing

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In this chapter, we will study about how to access the XML DOM nodes which are considered as the informational units of the XML document. The node structure of the XML DOM allows the developer to navigate around the tree looking for specific information and simultaneously access the information.

Accessing Nodes

Following are the three ways in which you can access the nodes −

  • By using the getElementsByTagName () method

  • By looping through or traversing through nodes tree

  • By navigating the node tree, using the node relationships

getElementsByTagName ()

This method allows accessing the information of a node by specifying the node name. It also allows accessing the information of the Node List and Node List Length.

Syntax

The getElementByTagName() method has the following syntax −

node.getElementByTagName("tagname");

Where,

  • node − is the document node.

  • tagname − holds the name of the node whose value you want to get.

Example

Following is a simple program which illustrates the usage of method getElementByTagName.

<!DOCTYPE html>
<html>
   <body>
      <div>
         <b>FirstName:</b> <span id = "FirstName"></span><br>
         <b>LastName:</b> <span id = "LastName"></span><br>
         <b>Category:</b> <span id = "Employee"></span><br>
      </div>
      <script>
         if (window.XMLHttpRequest) {// code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp = new XMLHttpRequest();
         } else {// code for IE6, IE5
            xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
         }
         xmlhttp.open("GET","/dom/node.xml",false);
         xmlhttp.send();
         xmlDoc = xmlhttp.responseXML;

         document.getElementById("FirstName").innerHTML = 
         xmlDoc.getElementsByTagName("FirstName")[0].childNodes[0].nodeValue;
         document.getElementById("LastName").innerHTML = 
         xmlDoc.getElementsByTagName("LastName")[0].childNodes[0].nodeValue;
         document.getElementById("Employee").innerHTML = 
         xmlDoc.getElementsByTagName("Employee")[0].attributes[0].nodeValue;
      </script>
   </body>
</html>

  • In the above example, we are accessing the information of the nodes FirstName, LastName and Employee.

  • xmlDoc.getElementsByTagName("FirstName")[0].childNodes[0].nodeValue; This line accesses the value for the child node FirstName using the getElementByTagName() method.

  • xmlDoc.getElementsByTagName("Employee")[0].attributes[0].nodeValue; This line accesses the attribute value of the node Employee getElementByTagName() method.

Traversing Through Nodes

This is covered in the chapter DOM Traversing with examples.

Navigating Through Nodes

This is covered in the chapter DOM Navigation with examples.

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