JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<html>
    <head>
        <title>Manipulate and Save XML</title>
    </head>
    <body>
        
        <div id="results"></div>
        <script type="text/xml" id="xml-data"><?xml version="1.0"?><project xmlns="http://fakenamespace.biz"><node></node></project></script>
    </body>
</html>

JavaScript

var xml_string = $("#xml-data").html();
try{
    
    var xml = $.parseXML(xml_string);
    var $xml = $(xml);
    var newStuff = $("<SelfClosingNode />");
    // var newStuff = "<SelfClosingNode />";
    $xml.find("project").append(newStuff);
    var new_xml_string = (new XMLSerializer()).serializeToString(xml);
    alert( new_xml_string );
    
} catch(e){
    
    alert(e);
    
}

//alert(xml);