use of @xmldom/xmldom in JavaScript to read and update nodes in an XML document

xpath-sample.js

const data = `<Foo>
  <Bar baz='17'>textvalue</Bar>
  <Baz>hello,world</Baz>
</Foo>`;

const xmldom      = require('@xmldom/xmldom'),
      DOMParser   = xmldom.DOMParser,
      xpath       = require('xpath'),
      doc         = new DOMParser().parseFromString(data),
      attr        = xpath.select('/Foo/Bar/@baz', doc)[0],
      elementText = xpath.select('/Foo/Baz/text()', doc)[0];

console.log(`attr.value=${attr.value}`);
console.log(`elementText=${elementText}`);

// attrValue=17
// elementText=hello,world

attr.value = '42'; // must be a string
const bazElement = xpath.select('/Foo/Baz', doc)[0];
bazElement.textContent = 'ciao, mondo';
const XMLSerializer = xmldom.XMLSerializer,
      serialized = new XMLSerializer().serializeToString(doc);
console.log(serialized);

// <Foo>
//   <Bar baz="42">textvalue</Bar>
//   <Baz>ciao, mondo</Baz>
// </Foo>