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XML DOM: Replace Nodes

Let's see how to replace an element node with replaceChild(), how to replace the data in a text node with replaceData() and with nodeValue property.

Replace an Element Node with replaceChild() Method​

The replaceChild() method replaces the specified node with the new node.

Syntax of replaceChild():

Node replaceChild(Node newChild, Node oldChild) throws DOMException

where:

  • newChild is the new node to put in the child list.
  • oldChild is the node being replaced in the list.
  • This method returns the node replaced.

Example of replacing the first <book> element with a new book:

xmlDoc = loadXMLDoc("/path/library.xml");
x = xmlDoc.documentElement;

//create a book element, title element and a text node  
newNode = xmlDoc.createElement("book");  
newTitle = xmlDoc.createElement("title");  
newText = xmlDoc.createTextNode("A New Book");  
  
//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("book")[0]  
//replace the first book node with the new node  
x.replaceChild(newNode,y);

Replace Data in a Text Node with replaceData() Method​

The replaceData() method is used to replace data in a text node.

void replaceData(offset, count, string) throws DOMException

The replaceData() method has three parameters:

  • offset is the offset from which to start replacing. Offset value starts at zero.
  • length is the number of characters to replace.
  • string is the string to insert.

Example: replace the eight first characters from the text node with "New String":

xmlDoc=loadXMLDoc("books.xml");  
x = xmlDoc.getElementsByTagName("title")[0].childNodes[0];  
x.replaceData(0,8,"New String");

Replace Data in a Text Node with nodeValue Property​

It is easier to replace data in a text node using the nodeValue property.

Let's look at the same example as before but using the nodeValue property:

xmlDoc=loadXMLDoc("books.xml");  
x=xmlDoc.getElementsByTagName("title")[0].childNodes[0];  
x.nodeValue="Easy Italian";
note

You can read more about changing node values in the Change Node chapter.

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