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 x, y, z, i, newNode, newTitle, newText, xmlDoc, txt;     xmlDoc = xml.responseXML;     txt = "";     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 Notebook");     // Add a 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 book node     x.replaceChild(newNode, y);     z = xmlDoc.getElementsByTagName("title");     // Output all titles     for (i = 0; i < z.length; i++) {         txt += z[i].childNodes[0].nodeValue + "<br>";     }     document.getElementById("demo").innerHTML = txt; }

elementNode.replaceChild(new_node,old_node)