Product
Socket Now Supports uv.lock Files
Socket now supports uv.lock files to ensure consistent, secure dependency resolution for Python projects and enhance supply chain security.
By Trevor Norris - Jan 09, 2025
Huge News!Announcing our $40M Series B led by Abstract Ventures.Learn More →
fast-xml-parser
Advanced tools
fast-xml-parser
Validate XML or Parse XML to JS/JSON very fast without C/C++ based libraries
What is fast-xml-parser?
The fast-xml-parser npm package is a fast and powerful XML parser and validator that can convert XML to a JavaScript object, JSON, or a traversable JS object. It can also convert a JS object to XML. It is designed to be very fast and efficient, and it provides various options to control the XML parsing and validation process.
What are fast-xml-parser's main functionalities?
XML to JSON Conversion
Converts XML data to a JSON object. The 'parse' function takes an XML string and optional options object, and returns a JSON representation of the XML.
const { parse } = require('fast-xml-parser');
const xmlData = '<note><to>User</to><from>Library</from><heading>Reminder</heading><body>Don't forget to subscribe.</body></note>';
const options = {};
const jsonObj = parse(xmlData, options);JSON to XML Conversion
Converts a JSON object to an XML string. The 'j2xParser' constructor takes an options object, and the 'parse' method converts the JSON object to an XML string.
const { j2xParser } = require('fast-xml-parser');
const parser = new j2xParser({});
const jsonObj = { note: { to: 'User', from: 'Library', heading: 'Reminder', body: 'Don't forget to subscribe.' } };
const xmlData = parser.parse(jsonObj);XML Validation
Validates the XML string. The 'validate' function checks if the given XML string is well-formed and returns a validation result.
const { validate } = require('fast-xml-parser');
const xmlData = '<note><to>User</to><from>Library</from></note>';
const validationResult = validate(xmlData);Traversable Object Creation
Creates a traversable JavaScript object from XML. The 'XMLParser' constructor creates a parser instance, and the 'parse' method converts the XML string into a traversable JS object.
const { XMLParser } = require('fast-xml-parser');
const xmlData = '<note><to>User</to><from>Library</from></note>';
const parser = new XMLParser();
const traversableObject = parser.parse(xmlData);Other packages similar to fast-xml-parser
xml2js
xml2js is a similar npm package that provides XML to JavaScript object conversion. It includes options to customize the parsing process and supports builder options for converting back to XML. Compared to fast-xml-parser, xml2js may be slower but offers a more feature-rich API for handling complex XML structures.
xml-js
xml-js is another npm package that converts XML text to a JavaScript object and vice versa. It can also convert XML to JSON and supports compact and non-compact modes. While fast-xml-parser focuses on speed, xml-js provides a more extensive set of conversion options.
libxmljs
libxmljs is a Node.js package that provides bindings to the libxml C library. It allows for parsing and serializing XML and includes XPath and XSLT support. It is different from fast-xml-parser in that it is a binding to a native library, which may offer performance benefits and additional XML processing features.
fast-xml-parser
Validate XML, Parse XML to JS/JSON and vice versa, or parse XML to Nimn rapidly without C/C++ based libraries and no callback
This project welcomes contributors. If you have a feature you'd like to see implemented or a bug you'd liked fixed, the best and fastest way to make that happen is to implement it and submit a PR. Basic knowledge of JS is sufficient. Feel free to ask for any guidance.
Users
List of some applications/projects using Fast XML Parser. (Raise an issue to submit yours)
Join this project as collaborator / maintainer.
Main Features
- Validate XML data syntactically
- Transform XML to JSON or Nimn
- Transform JSON back to XML
- Works with node packages, in browser, and in CLI (press try me button above for demo)
- Faster than any pure JS implementation.
- It can handle big files (tested up to 100mb).
- Various options are available to customize the transformation
- You can parse CDATA as separate property.
- You can prefix attributes or group them to separate property. Or can ignore them from result completely.
- You can parse tag's or attribute's value to primitive type: string, integer, float, hexadecimal, or boolean. And can optionally decode for HTML char.
- You can remove namespace from tag or attribute name while parsing
- It supports boolean attributes, if configured.
How to use
To use it in NPM package install it first
$npm install fast-xml-parser or using yarn $yarn add fast-xml-parser
To use it from CLI Install it globally with -g option.
$npm install fast-xml-parser -g
To use it on a webpage include it from a CDN
XML to JSON
var jsonObj = parser.parse(xmlData [,options] );
var parser = require('fast-xml-parser');
var he = require('he');
var options = {
attributeNamePrefix : "@_",
attrNodeName: "attr", //default is 'false'
textNodeName : "#text",
ignoreAttributes : true,
ignoreNameSpace : false,
allowBooleanAttributes : false,
parseNodeValue : true,
parseAttributeValue : false,
trimValues: true,
cdataTagName: "__cdata", //default is 'false'
cdataPositionChar: "\\c",
localeRange: "", //To support non english character in tag/attribute values.
parseTrueNumberOnly: false,
attrValueProcessor: a => he.decode(a, {isAttributeValue: true}),//default is a=>a
tagValueProcessor : a => he.decode(a) //default is a=>a
};
if( parser.validate(xmlData) === true) { //optional (it'll return an object in case it's not valid)
var jsonObj = parser.parse(xmlData,options);
}
// Intermediate obj
var tObj = parser.getTraversalObj(xmlData,options);
var jsonObj = parser.convertToJson(tObj,options);
Note: he library is used in this example
OPTIONS :
- attributeNamePrefix : prepend given string to attribute name for identification
- attrNodeName: (Valid name) Group all the attributes as properties of given name.
- ignoreAttributes : Ignore attributes to be parsed.
- ignoreNameSpace : Remove namespace string from tag and attribute names.
- allowBooleanAttributes : a tag can have attributes without any value
- parseNodeValue : Parse the value of text node to float, integer, or boolean.
- parseAttributeValue : Parse the value of an attribute to float, integer, or boolean.
- trimValues : trim string values of an attribute or node
- decodeHTMLchar : This options has been removed from 3.3.4. Instead, use tagValueProcessor, and attrValueProcessor. See above example.
- cdataTagName : If specified, parser parse CDATA as nested tag instead of adding it's value to parent tag.
- cdataPositionChar : It'll help to covert JSON back to XML without losing CDATA position.
- localeRange: Parser will accept non-English character in tag or attribute name. Check #87 for more detail. Eg
localeRange: "a-zA-Zа-яёА-ЯЁ" - parseTrueNumberOnly: if true then values like "+123", or "0123" will not be parsed as number.
- tagValueProcessor : Process tag value during transformation. Like HTML decoding, word capitalization, etc. Applicable in case of string only.
- attrValueProcessor : Process attribute value during transformation. Like HTML decoding, word capitalization, etc. Applicable in case of string only.
- stopNodes : an array of tag names which are not required to be parsed. Instead their values are parsed as string.
To use from command line
$xml2js [-ns|-a|-c|-v|-V] <filename> [-o outputfile.json]
$cat xmlfile.xml | xml2js [-ns|-a|-c|-v|-V] [-o outputfile.json]
- -ns : To include namespaces (by default ignored)
- -a : To ignore attributes
- -c : To ignore value conversion (i.e. "-3" will not be converted to number -3)
- -v : validate before parsing
- -V : only validate
To use it on webpage
var result = parser.validate(xmlData);
if (result !== true) console.log(result.err);
var jsonObj = parser.parse(xmlData);
JSON / JS Object to XML
var Parser = require("fast-xml-parser").j2xParser;
//default options need not to set
var defaultOptions = {
attributeNamePrefix : "@_",
attrNodeName: "@", //default is false
textNodeName : "#text",
ignoreAttributes : true,
cdataTagName: "__cdata", //default is false
cdataPositionChar: "\\c",
format: false,
indentBy: " ",
supressEmptyNode: false,
tagValueProcessor: a=> he.encode(a, { useNamedReferences: true}),// default is a=>a
attrValueProcessor: a=> he.encode(a, {isAttributeValue: isAttribute, useNamedReferences: true})// default is a=>a
};
var parser = new Parser(defaultOptions);
var xml = parser.parse(json_or_js_obj);
OPTIONS :
With the correct options, you can get the almost original XML without losing any information.
- attributeNamePrefix : Identify attributes with this prefix otherwise treat them as a tag.
- attrNodeName: Identify attributes when they are grouped under single property.
- ignoreAttributes : Don't check for attributes. Treats everything as tag.
- encodeHTMLchar : This option has been removed from 3.3.4. Use tagValueProcessor, and attrValueProcessor instead. See above example.
- cdataTagName : If specified, parse matching tag as CDATA
- cdataPositionChar : Identify the position where CDATA tag should be placed. If it is blank then CDATA will be added in the last of tag's value.
- format : If set to true, then format the XML output.
- indentBy : indent by this char
whenformat is set totrue - supressEmptyNode : If set to
true, tags with no value (text or nested tags) are written as self closing tags. - tagValueProcessor : Process tag value during transformation. Like HTML encoding, word capitalization, etc. Applicable in case of string only.
- attrValueProcessor : Process attribute value during transformation. Like HTML encoding, word capitalization, etc. Applicable in case of string only.
Benchmark
XML to JSON
report
| file size | fxp 3.0 validator (rps) | fxp 3.0 parser (rps) | xml2js 0.4.19 (rps) |
|---|---|---|---|
| 1.5k | 16581.06758 | 14032.09323 | 4615.930805 |
| 1.5m | 14918.47793 | 13.23366098 | 5.90682005 |
| 13m | 1.834479235 | 1.135582008 | -1 |
| 1.3k with CDATA | 30583.35319 | 43160.52342 | 8398.556349 |
| 1.3m with CDATA | 27.29266471 | 52.68877009 | 7.966000795 |
| 1.6k with cdata,prolog,doctype | 27690.26082 | 41433.98547 | 7872.399268 |
| 98m | 0.08473858148 | 0.2600104004 | -1 |
- -1 indicates error or incorrect output.
JSON to XML
report
| file size | fxp 3.2 js to xml | xml2js 0.4.19 builder |
|---|---|---|
| 1.3k | 160148.9801 | 10384.99401 |
| 1.1m | 173.6374831 | 8.611884025 |
Limitations
Currently FXP fails to parse XML with attributes has ">" in the value. This problem is left open as change in regex for its fix is degrading the performance. And the parser become very slow in case of long attrbute names.
Worth to mention
- BigBit standard) : A standard to reprent any number in the universe in comparitively less space and without precision loss. A standard to save space to represent any text string in comparision of UTF encoding.
- imglab : Speedup and simplify image labeling / annotation. Supports multiple formats, one click annotation, easy interface and much more. There are more than 20k images are annotated every month.
- अनुमार्गक (anumargak) : The fastest and simple router for node js web frameworks with many unique features.
- stubmatic : A stub server to mock behaviour of HTTP(s) / REST / SOAP services, incuding DynamoDB calls. You can also mock binary formats.
- मुनीम (Muneem) : A webframework made for all team members. Faster tha fastify, express, koa, hapi and others.
- शब्दावली (shabdawali) : Amazing human like typing effects beyond your imagination.
Contributors
This project exists thanks to all the people who contribute. [Contribute].
Backers
Thank you to all our backers! 🙏 [Become a backer]
Sponsors
Support this project by becoming a sponsor. Your logo will show up here with a link to your website. [Become a sponsor]
FAQs
Validate XML, Parse XML, Build XML without C/C++ based libraries
The npm package fast-xml-parser receives a total of 11,369,770 weekly downloads. As such, fast-xml-parser popularity was classified as popular.
We found that fast-xml-parser demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 0 open source maintainers collaborating on the project.
Package last updated on 16 Aug 2019
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Related posts
Research
Security News
Gmail For Exfiltration: Malicious npm Packages Target Solana Private Keys and Drain Victims' Wallets
Socket researchers have discovered multiple malicious npm packages targeting Solana private keys, abusing Gmail to exfiltrate the data and drain Solana wallets.
By Kirill Boychenko - Jan 08, 2025
Security News
New Python Packaging Proposal Aims to Solve Phantom Dependency Problem with SBOMs
PEP 770 proposes adding SBOM support to Python packages to improve transparency and catch hidden non-Python dependencies that security tools often miss.
By Sarah Gooding - Jan 07, 2025