XML DOM Replace Nodes

Examples

In the examples below, we will use the XML file books.xml, and the JavaScript function loadXMLDoc().

Replace a node in a nodelist
This example uses replaceChild() to replace the last child in a node list.

Replace data in a text node
This example uses replaceData() to replace data in a text node.

Replace a Node in a Node List

The replaceChild() method is used to replace a node in a node list.

The following code fragment creates a new <book> element that will replace the last <book> element:

//check if last child node is an element node
            function get_lastchild(n)
            {
            var x=n.lastChild;
            while (x.nodeType!=1)
            {
            x=x.previousSibling;
            }
            return x;
            }

xmlDoc=loadXMLDoc("books.xml");

var x=xmlDoc.documentElement;

//create a book element, title element and a text node
            var newNode=xmlDoc.createElement("book");
            var newTitle=xmlDoc.createElement("title");
            var newText=xmlDoc.createTextNode("A Notebook");

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

//replace the last node with the new node
            x.replaceChild(newNode,get_lastchild(x));

Note: Internet Explorer will skip white-space text nodes that are generated between nodes (e.g. new-line characters), while Mozilla will not. So, in the example above, the get_lastchild() function checks the node type of the last child node of the parameter.

Element nodes has a nodeType of 1, so if not the last child of the node in the parameter is an element node, it moves to the previous node, and checks if this node is an element node. This continues until the last child node (which must be an element node) is found. This way, the result will be correct in both Internet Explorer and Mozilla.

Replace Data In a Text Node

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

The replaceData() method has three parameters:

• offset - Where to begin replacing characters. Offset value starts at zero
• length - How many characters to replace
• string - The string to insert

The following code fragment will replace the eight first characters from the text node in the first <title> element with "Easy":

xmlDoc=loadXMLDoc("books.xml");

var x=xmlDoc.getElementsByTagName("title")[0].childNodes[0];

x.replaceData(0,8,"Easy");