XML DOM - Replace Node

In this chapter, we will study about the replace node operation in an XML DOM object. As we know everything in the DOM is maintained in a hierarchical informational unit known as node and the replacing node provides another way to update these specified nodes or a text node.
Following are the two methods to replace the nodes.
replaceChild()
replaceData()
The method replaceChild() replaces the specified node with the new node.
The insertData() has the following syntax −
Node replaceChild(Node newChild, Node oldChild) throws DOMException

Where,
newChild − is the new node to put in the child list.
newChild − is the new node to put in the child list.
oldChild − is the node being replaced in the list.
oldChild − is the node being replaced in the list.
This method returns the node replaced.
This method returns the node replaced.
The following example (replacenode_example.htm) parses an XML document (node.xml) into an XML DOM object and replaces the specified node <FirstName> with the new node <Name>.
<!DOCTYPE html>
<html>
   <head>
      <script>
         function loadXMLDoc(filename) {
            if (window.XMLHttpRequest) {
               xhttp = new XMLHttpRequest();
            } else // code for IE5 and IE6 {
               xhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            xhttp.open("GET",filename,false);
            xhttp.send();
            return xhttp.responseXML;
         }
      </script>
   </head>
   <body>
      <script>
         xmlDoc = loadXMLDoc("/dom/node.xml");

         x = xmlDoc.documentElement;

         z = xmlDoc.getElementsByTagName("FirstName");
         document.write("<b>Content of FirstName element before replace operation</b><br>");
         for (i=0;i<z.length;i++) {
            document.write(z[i].childNodes[0].nodeValue);
            document.write("<br>");
         }
         //create a Employee element, FirstName element and a text node
         newNode = xmlDoc.createElement("Employee");
         newTitle = xmlDoc.createElement("Name");
         newText = xmlDoc.createTextNode("MS Dhoni");

         //add the text node to the title node,
         newTitle.appendChild(newText);
         //add the title node to the book node
         newNode.appendChild(newTitle);

         y = xmlDoc.getElementsByTagName("Employee")[0]
         //replace the first book node with the new node
         x.replaceChild(newNode,y);

         z = xmlDoc.getElementsByTagName("FirstName");
         document.write("<b>Content of FirstName element after replace operation</b><br>");
         for (i = 0;i<z.length;i++) {
            document.write(z[i].childNodes[0].nodeValue);
            document.write("<br>");
         }
      </script>
   </body>
</html>
Save this file as replacenode_example.htm on the server path (this file and node.xml should be on the same path in your server). We will get the output as shown below −
Content of FirstName element before replace operation
Tanmay
Taniya
Tanisha

Content of FirstName element after replace operation
Taniya
Tanisha

The method replaceData() replaces the characters starting at the specified 16-bit unit offset with the specified string.
The replaceData() has the following syntax −
void replaceData(int offset, int count, java.lang.String arg) throws DOMException

Where
offset − is the offset from which to start replacing.
offset − is the offset from which to start replacing.
count − is the number of 16-bit units to replace. If the sum of offset and count exceeds length, then all the 16-bit units to the end of the data are replaced.
count − is the number of 16-bit units to replace. If the sum of offset and count exceeds length, then all the 16-bit units to the end of the data are replaced.
arg − the DOMString with which the range must be replaced.
arg − the DOMString with which the range must be replaced.
The following example (replacedata_example.htm) parses an XML document (node.xml) into an XML DOM object and replaces it.
<!DOCTYPE html>
<html>
   <head>
      <script>
         function loadXMLDoc(filename) {
            if (window.XMLHttpRequest) {
               xhttp = new XMLHttpRequest();
            } else // code for IE5 and IE6 {
               xhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            xhttp.open("GET",filename,false);
            xhttp.send();
            return xhttp.responseXML;
         }
      </script>
   </head>
   <body>
      <script>
         xmlDoc = loadXMLDoc("/dom/node.xml");

         x = xmlDoc.getElementsByTagName("ContactNo")[0].childNodes[0];
         document.write("<b>ContactNo before replace operation:</b> "+x.nodeValue);
         x.replaceData(1,5,"9999999");
         document.write("<br>");
         document.write("<b>ContactNo after replace operation:</b> "+x.nodeValue);

      </script>
   </body>
</html>
In the above example −
x.replaceData(2,3,"999"); − Here x holds the text of the specified element <ContactNo> whose text is replaced by the new text "9999999", starting from the position 1 till the length of 5.
x.replaceData(2,3,"999"); − Here x holds the text of the specified element <ContactNo> whose text is replaced by the new text "9999999", starting from the position 1 till the length of 5.
Save this file as replacedata_example.htm on the server path (this file and node.xml should be on the same path in your server). We will get the output as shown below −
ContactNo before replace operation: 1234567890

ContactNo after replace operation: 199999997890 


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