Working with XML in JavaScript (Node.js): Libraries and Examples

Working with XML in JavaScript (Node.js): Libraries, Parsing and Creation

XML (eXtensible Markup Language) remains a popular format for data exchange in corporate systems, configuration files, and legacy APIs. In the Node.js ecosystem, there are several mature libraries that allow you to efficiently parse, create, and transform XML documents. In this article, we will look at three of the most popular libraries: fast-xml-parser, xml2js and libxmljs, and also show practical examples of their use.

1. fast-xml-parser — fast and secure parser

fast-xml-parser is one of the most performant libraries for working with XML in Node.js. It supports both synchronous and asynchronous parsing, and can also validate XML documents against XSD schemas.

Installation

npm install fast-xml-parser

Example of parsing XML into a JavaScript object

const { XMLParser } = require('fast-xml-parser');

const xmlData = `<?xml version="1.0" encoding="UTF-8"?><bookstore>    <book category="programming">        <title lang="en">JavaScript: The Good Parts</title>        <author>Douglas Crockford</author>        <year>2008</year>        <price>29.99</price>    </book></bookstore>`;

const parser = new XMLParser({    ignoreAttributes: false,    attributeNamePrefix: '@_'});

const result = parser.parse(xmlData);console.log(JSON.stringify(result, null, 2));

The ignoreAttributes: false setting allows you to preserve XML tag attributes, and attributeNamePrefix adds a prefix to attribute names to prevent conflicts with regular tags.

Creating XML from an object

const { XMLBuilder } = require('fast-xml-parser');

const builder = new XMLBuilder({    format: true,    ignoreAttributes: false});

const obj = {    bookstore: {        book: {            '@_category': 'programming',            title: { '@_lang': 'en', '#text': 'Clean Code' },            author: 'Robert C. Martin',            year: 2008,            price: 39.99        }    }};

const xmlOutput = builder.build(obj);console.log(xmlOutput);

2. xml2js — simple and reliable converter

xml2js is a classic library for converting XML to JSON and back. It provides a simple API and is well documented.

Installation

npm install xml2js

Parsing XML with error handling

const xml2js = require('xml2js');const fs = require('fs');

const parser = new xml2js.Parser({    explicitArray: false, // do not wrap single elements in arrays    trim: true,    normalizeTags: true   // normalize tag case});

fs.readFile('config.xml', 'utf-8', (err, data) => {    if (err) {        console.error('Error reading file:', err);        return;    }        parser.parseString(data, (parseErr, result) => {        if (parseErr) {            console.error('Error parsing XML:', parseErr);            return;        }        console.log('Configuration parameters:', result.configuration);    });});

Creating XML with xml2js

const xml2js = require('xml2js');

const builder = new xml2js.Builder({    xmldec: { version: '1.0', encoding: 'UTF-8' },    renderOpts: { pretty: true, indent: '  ' }});

const obj = {    response: {        status: 'success',        data: {            user: {                id: 123,                name: 'Ivan Petrov',                email: 'ivan@example.com'            }        }    }};

const xml = builder.buildObject(obj);console.log(xml);

3. libxmljs — for advanced XML work

l