How to Parse XML in Python, JavaScript, and the Browser

Pick a Parser Style

XML parsers come in two families. DOM-style parsers load the whole document into a tree—simple and fine for small files. Streaming (SAX/StAX/iterparse) parsers emit events as they read—required for large feeds.

Never build a parser with regex. Quoting, CDATA, namespaces, and nested tags will break hand-rolled patterns.

Step-by-Step: Parse XML in Python

ElementTree is in the standard library and covers most jobs.

import xml.etree.ElementTree as ET

root = ET.parse("orders.xml").getroot()
for item in root.findall(".//item"):
    sku = item.get("sku")
    name = (item.findtext("name") or "").strip()
    print(sku, name)

for _event, elem in ET.iterparse("big.xml", events=("end",)):
    if elem.tag.endswith("item"):
        process(elem)
        elem.clear()

ns = {"p": "https://example.com/products"}
for item in root.findall(".//p:item", ns):
    print(item.get("sku"))

Step-by-Step: Parse XML in the Browser

DOMParser turns a string into a Document you can query.

const xml = await file.text();
const doc = new DOMParser().parseFromString(xml, "application/xml");
const parseError = doc.querySelector("parsererror");
if (parseError) throw new Error(parseError.textContent);

const items = [...doc.querySelectorAll("item")].map((el) => ({
  sku: el.getAttribute("sku"),
  name: el.querySelector("name")?.textContent?.trim() ?? "",
}));

Step-by-Step: Parse XML in Node.js

fast-xml-parser is a popular choice for converting XML to plain objects.

import { XMLParser } from "fast-xml-parser";
import fs from "node:fs";

const parser = new XMLParser({
  ignoreAttributes: false,
  attributeNamePrefix: "",
});
const data = parser.parse(fs.readFileSync("orders.xml", "utf8"));
console.log(data);

From Parsed XML to CSV or JSON

After parsing, most teams want a table or a JSON array. Map repeating elements to rows, attributes and children to columns, then write CSV—or skip the code for one-offs with the XML to CSV Converter on Convert CSV Online.

Security Notes

Untrusted XML can abuse entity expansion (XXE) and billion-laughs attacks. Disable external entity resolution unless you fully trust the source. Prefer hardened libraries and defaults that reject external DTDs.

Real-World Examples

Where parsing shows up daily.

Common Mistakes

These burn hours on otherwise simple jobs.

• Ignoring namespaces and getting empty NodeLists.
• Loading a huge file into a DOM when streaming would work.
• Treating textContent as trimmed when surrounding whitespace matters.
• Assuming attributes and child elements with the same name are interchangeable.
• Enabling external entities on untrusted input.

Best Practices

Keep parsing boring and safe.

• Validate well-formedness first, then parse.
• Handle namespaces explicitly.
• Stream large documents.
• Disable external entities by default.
• Convert to CSV/JSON only after you know the repeating row element.

Why Use Convert CSV Online?

When you only need a spreadsheet view, Convert CSV Online is free, browser-based, and requires no account for everyday conversions. Flatten with XML to CSV, edit in the Online CSV Editor, and skip writing a one-off parser. Client-side workflows work on Windows, macOS, and Linux browsers.

Conclusion

Parsing XML is choosing the right tool—tree for small docs, streams for large ones—then handling namespaces and attributes deliberately. Convert to CSV when humans need a table.