xunfeiAI/static/fast-xml-parser

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

Users

List of some applications/projects using Fast XML Parser. (Raise an issue to submit yours)

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 a separate property.
  • You can prefix attributes or group them to a separate property. Or they can be ignored from the 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 a CLI install it globally with the -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",
    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 the above code, validator is not embedded 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,
  },
};

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.
• parseTrueNumberOnly: if true then values like "+123", or "0123" will not be parsed as number.
• arrayMode : When false, a tag with single occurrence 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.
• 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 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.

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 attribute names. However, it is not ignored and we're working on the fix.

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Contributors

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Backers

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