fast-xml-parser
Advanced tools
Validate XML or Parse XML to JS/JSON very fast without C/C++ based libraries
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.
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);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 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 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.
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.
List of some applications/projects using Fast XML Parser. (Raise an issue to submit yours)
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.
$npm install fast-xml-parser -g
To use it on a webpage include it from a CDN
var jsonObj = parser.parse(xmlData [,options] );
var parser = require('fast-xml-parser');
var he = require('he');
var options = {
attributeNamePrefix : "@_",
attrNodeName: "attr", //default is 'false'
textNodeName : "#text",
ignoreAttributes : true,
ignoreNameSpace : false,
allowBooleanAttributes : false,
parseNodeValue : true,
parseAttributeValue : false,
trimValues: true,
cdataTagName: "__cdata", //default is 'false'
cdataPositionChar: "\\c",
parseTrueNumberOnly: false,
arrayMode: false, //"strict"
attrValueProcessor: (val, attrName) => he.decode(val, {isAttributeValue: true}),//default is a=>a
tagValueProcessor : (val, tagName) => he.decode(val), //default is a=>a
stopNodes: ["parse-me-as-string"]
};
if( parser.validate(xmlData) === true) { //optional (it'll return an object in case it's not valid)
var jsonObj = parser.parse(xmlData,options);
}
// Intermediate obj
var tObj = parser.getTraversalObj(xmlData,options);
var jsonObj = parser.convertToJson(tObj,options);
As you can notice in above code, validator is not embeded with in the parser and expected to be called separately. However, you can pass true or validation options as 3rd parameter to the parser to trigger validator internally. It is same as above example.
try{
var jsonObj = parser.parse(xmlData,options, true);
}catch(error){
console.log(error.message)
}
Validator returns the following object in case of error;
{
err: {
code: code,
msg: message,
line: lineNumber,
},
};
false, a tag with single occurence is parsed as an object but as an array in case of multiple occurences. When true, a tag will be parsed as an array always excluding leaf nodes. When strict, all the tags will be parsed as array only.$xml2js [-ns|-a|-c|-v|-V] <filename> [-o outputfile.json]
$cat xmlfile.xml | xml2js [-ns|-a|-c|-v|-V] [-o outputfile.json]
var result = parser.validate(xmlData);
if (result !== true) console.log(result.err);
var jsonObj = parser.parse(xmlData);
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);
With the correct options, you can get the almost original XML without losing any information.
when format is set to truetrue, tags with no value (text or nested tags) are written as self closing tags.
| 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 |
| 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 |
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. Hoever, It is not ignored and we're working on the fix.
This project exists thanks to all the people who contribute. [Contribute].
Thank you to all our backers! 🙏 [Become a backer]
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 21,629,164 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.
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