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

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, 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 parser.js or directly from CDN

XML to JSON or XML to Nimn

var fastXmlParser = require('fast-xml-parser');
var jsonObj = fastXmlParser.parse(xmlData);
//construct schema manually or with the help of schema builder
var nimndata = fastXmlParser.parseToNimn(xmlData,schema);
//or
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",
    attrValueProcessor: a => he.decode(a, {isAttributeValue: true}),//default is a=>a
    tagValueProcessor : a => he.decode(a) //default is a=>a
};
if(fastXmlParser.validate(xmlData)=== true){//optional
	var jsonObj = fastXmlParser.parse(xmlData,options);
}

//Intermediate obj
var tObj = fastXmlParser.getTraversalObj(xmlData,options);
var jsonObj = fastXmlParser.convertToJson(tObj,options);

//construct schema manually or with the help of schema builder
var nimndata = fastXmlParser.convertTonimn(tObj,schema,options);

NIMN (निम्न) data is the schema aware compressed form of data. It reduces JSON up to 50% or more of original data by removing field information. Check specification for more detail.
Check nimnjs to know more about schema, json to nimndata and reverse transformation.

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.
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.

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) cnosole.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 when format is set to true
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.

Comparision

We've compared various libraries which transforms XML to JS. Most of them either are dependent on C/C++ libraries, or slow, or don't do reverse transformation.

Why not C/C++ based libraries? C/C++ based libraries are no doubt faster than this library but they don't run in browser, and a user need to install extra supporting libraries on their computer.

Benchmark 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.

Benchmark for JSON to XML

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

Worth to mention

निम्न (NIMN) : Schema aware object compression. 60% more compressed than JSON. 40% more compressed than msgpack.
imglab : Web based tool to label images for object. So that they can be used to train dlib or other object detectors. You can integrate 3rd party libraries for fast labeling.
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fast-lorem-ipsum : Generate lorem ipsum words, sentences, paragraph very quickly.
stubmatic : A stub server to mock behaviour of HTTP(s) / REST / SOAP services. You can also mock msgpack, and nimn format in easy way.
fastify-xml-body-parser : Fastify plugin / module to parse XML payload / body into JS object using fast-xml-parser.
Grapes : Flexible Regular expression engine (for java) which can be applied on char stream. (under development)