Convert XML document to JSON

xmlToJson.js

// const xmlDoc = new DOMParser().parseFromString(xmlString, 'text/xml');
function xmlToJson(xml) {
  const parseAll = s => (s && ((!isNaN(s) && parseFloat(s)) || (Date.parse(s) && new Date(s)))) || s.trim();
  const nodesToJson = function(nodes) {
    return Array.from(nodes || [])
      .map(item => ({
        name: item.nodeName,
        value: item.nodeType === Node.ATTRIBUTE_NODE ? parseAll(item.nodeValue) : xmlToJson(item)
      }))
      .filter(item => item.value)
      .reduce((result, { name, value }) => {
        if (typeof result[name] === 'undefined') {
          result[name] = value;
        } else {
          if (typeof result[name].push === 'undefined') {
            result[name] = [result[name]];
          }
          result[name].push(value);
        }
        return result;
      }, Object.create(null));
  };

  if (xml.nodeType === Node.TEXT_NODE) return parseAll(xml.nodeValue);
  const attributes = xml.nodeType === Node.ELEMENT_NODE ? nodesToJson(xml.attributes) : {},
    children = xml.hasChildNodes() ? nodesToJson(xml.childNodes) : {},
    result = { ...attributes, ...children };
  return Object.keys(result).length === 1 ? Object.values(result)[0] : result;
}