What is xml-js?
The xml-js npm package is a utility that provides methods to convert between XML and JSON format. It can also convert between XML and JavaScript objects. This package is useful when working with XML data in JavaScript environments where JSON is more easily manipulated.
What are xml-js's main functionalities?
XML to JSON Conversion
Converts an XML string to a JSON string. The options object can be used to customize the output.
const convert = require('xml-js');
const xml = '<note><to>User</to><from>Library</from><heading>Reminder</heading><body>Don't forget me this weekend!</body></note>';
const options = {compact: true, ignoreComment: true, spaces: 4};
const result = convert.xml2json(xml, options);
console.log(result);
JSON to XML Conversion
Converts a JSON string to an XML string. The options object can be used to customize the output.
const convert = require('xml-js');
const json = '{"note":{"to":"User","from":"Library","heading":"Reminder","body":"Don't forget me this weekend!"}}';
const options = {compact: true, ignoreComment: true, spaces: 4};
const result = convert.json2xml(json, options);
console.log(result);
XML to JavaScript Object
Converts an XML string to a JavaScript object. The options object can be used to customize the output.
const convert = require('xml-js');
const xml = '<note><to>User</to><from>Library</from><heading>Reminder</heading><body>Don't forget me this weekend!</body></note>';
const result = convert.xml2js(xml, {compact: true, spaces: 4});
console.log(result);
JavaScript Object to XML
Converts a JavaScript object to an XML string. The options object can be used to customize the output.
const convert = require('xml-js');
const jsObject = {
note: {
to: 'User',
from: 'Library',
heading: 'Reminder',
body: 'Don't forget me this weekend!'
}
};
const options = {compact: true, spaces: 4};
const result = convert.js2xml(jsObject, options);
console.log(result);
Other packages similar to xml-js
fast-xml-parser
A very fast XML parser and validator with a similar feature set to xml-js. It can parse XML to a JavaScript object/JSON and vice versa. It is known for its performance and, unlike xml-js, includes XML validation.
xml2js
Another popular XML to JavaScript converter that provides a similar conversion functionality as xml-js. It includes options to customize the parser behavior and, like xml-js, it does not validate the XML.
xmlbuilder
This package allows for building XML documents from JavaScript objects, focusing on the creation of XML content. It is more specialized in generating XML and does not provide parsing from XML to JavaScript objects.
Convert XML text to Javascript object / JSON text (and vice versa).
Synopsis
Motivation
There are many XML to JavaScript object / JSON converters out there, but could not satisfy the following requirements:
-
Maintain Order of Sub-elements:
Instead of converting <a/><b/><a/>
to {a:[{},{}],b:{}}
, I wanted to preserve order of elements by doing this:
{"elements":[{"type":"element","name":"a"},{"type":"element","name":"b"},{"type":"element","name":"a"}]}
.
-
Fully XML Compliant:
Can parse: elements, attributes, texts, comments, CData, and XML declarations.
-
Reversible:
Whether converting xml→json or json→xml, the result should be convertable to its original form.
-
Minimal Dependencies:
This library depends only on one external npm module.
-
Change Property Key Name:
Usually output of XML attributes are stored in @attr
, _atrr
, $attr
, $
, or whatever
in order to avoid conflicting with name of sub-elements.
This library store them in attributes
, but most importantly, you can change this to whatever you like.
-
Portable Code:
Written purely in JavaScript which means it can be used in Node environment and browser environment (via bundlers like browserify/JSPM/Webpack).
Note (this is default behavior, but this can be slow for very large XML text).
-
Support Command Line:
To quickly convert xml or json files, this module can be installed globally or locally (i.e. use it as script in package.json).
-
Typings Info Included:
Support type checking and code suggestion via intellisense.
Thanks to the wonderful efforts by DenisCarriere
Compact vs Non-Compact
Most XML to JSON convertors (including online convertors) convert <a/>
to some compact output like {"a":{}}
instead of non-compact output like {"elements":[{"type":"element","name":"a"}]}
.
While compact output might work in most situations, there are cases when different elements are mixed inside a parent element: <a x="1"/><b x="2"/><a x="3"/>
.
In this case, the compact output will be something like {a:[{_:{x:"1"}},{_:{x:"3"}}],b:{_:{x:"2"}}}
,
which has merged both <a>
elements into an array. If you try to convert this back to xml, you will get <a x="1"/><a x="3"/><b x="2"/>
which has not preserved the order of elements! This is an inherit limitation in the compact representation
because output like {a:{_:{x:"1"}},b:{_:{x:"2"}},a:{_:{x:"3"}}}
is illegal.
Note that this issue does not occur in the non-compact form provided by this library.
Although non-compact output is more accurate representation of original XML than compact version, the non-compact consumes more space.
This library provides both options. Use {compact: false}
if you are not sure because it preserves everything;
otherwise use {compact: true}
if you want to save space and you don't care about mixing elements of same type and loosing their order.
Usage
Installation
npm install --save xml-js
You can also installed it globally to use it as a command line convertor.
npm install --global xml-js
Quick start
var convert = require('xml-js');
var xml =
'<?xml version="1.0" encoding="utf-8"?>' +
'<note importance="high" logged="true">' +
' <title>Happy</title>' +
' <todo>Work</todo>' +
' <todo>Play</todo>' +
'</note>';
var result1 = convert.xml2json(xml, {compact: true, spaces: 4});
var result2 = convert.xml2json(xml, {compact: false, spaces: 4});
console.log(result1, '\n', result2);
To see the result of this code, see the output above in Synopsis section.
Sample Conversions
XML | JS/JSON compact | JS/JSON non-compact |
---|
<?xml?> | {"_declaration":{}} | {"declaration":{}} |
<?xml version="1.0" encoding="utf-8"?> | {"_declaration":{"_attributes":{"version":"1.0","encoding":"utf-8"}}} | {"declaration":{"attributes":{"version":"1.0","encoding":"utf-8"}}} |
<!--Hello, World!--> | {"_comment":"Hello, World!"} | {"elements":[{"type":"comment","comment":"Hello, World!"}]} |
<![CDATA[<foo></bar>]]> | {"_cdata":"<foo></bar>"} | {"elements":[{"type":"cdata","cdata":"<foo></bar>"}]} |
<a/> | {"a":{}} | {"elements":[{"type":"element","name":"a"}]} |
<a x="1.234" y="It's"/> | {"a":{"_attributes":{"x":"1.234","y":"It's"}}} | {"elements":[{"type":"element","name":"a","attributes":{"x":"1.234","y":"It's"}}]} |
<a> Hi </a> | {"a":{"_text":" Hi "}} | {"elements":[{"type":"element","name":"a","elements":[{"type":"text","text":" Hi "}]}]} |
<a/><b/> | {"a":{},"b":{}} | {"elements":[{"type":"element","name":"a"},{"type":"element","name":"b"}]} |
<a><b/></a> | {"a":{"b":{}}} | {"elements":[{"type":"element","name":"a","elements":[{"type":"element","name":"b"}]}]} |
API Reference
Convert JS object / JSON → XML
To convert JavaScript object to XML text, use js2xml()
. To convert JSON text to XML text, use json2xml()
.
var convert = require('xml-js');
var json = require('fs').readFileSync('test.json', 'utf8');
var options = {ignoreText: true, spaces: 4};
var result = convert.json2xml(json, options);
console.log(result);
Options for Converting JS object / JSON → XML
The below options are applicable for both js2xml()
and json2xml()
functions.
Option | Default | Description |
---|
spaces | 0 | Number of spaces to be used for indenting XML output. |
compact | false | Whether the input object is in compact form or not. |
fullTagEmptyElement | false | Whether to produce element without sub-elements as full tag pairs <a></a> rather than self closing tag <a/> . |
ignoreDeclaration | false | Whether to ignore writing declaration directives of xml. For example, <?xml?> will be ignored. |
ignoreAttributes | false | Whether to ignore writing attributes of the elements. For example, x="1" in <a x="1"></a> will be ignored |
ignoreComment | false | Whether to ignore writing comments of the elements. That is, no <!-- --> will be generated. |
ignoreCdata | false | Whether to ignore writing CData of the elements. That is, no <![CDATA[ ]]> will be generated. |
ignoreText | false | Whether to ignore writing texts of the elements. For example, hi text in <a>hi</a> will be ignored. |
Convert XML → JS object / JSON
To convert XML text to JavaScript object, use xml2js()
. To convert XML text to JSON text, use xml2json()
.
var convert = require('xml-js');
var xml = require('fs').readFileSync('test.xml', 'utf8');
var options = {ignoreText: true, alwaysChildren: true};
var result = convert.xml2js(xml, options);
console.log(result);
Options for Converting XML → JS object / JSON
The below options are applicable for both xml2js()
and xml2json()
functions.
Option | Default | Description |
---|
compact | false | Whether to produce detailed object or compact object. |
trim | false | Whether to trim white space characters that may exist before and after the text. |
sanitize | false | Whether to replace & < > " ' with & < > " ' respectively in the resultant text. |
nativeType | false | whether to attempt converting text of numerals or of boolean values to native type. For example, "123" will be 123 and "true" will be true |
addParent | false | Whether to add parent property in each element object that points to parent object. |
alwaysChildren | false | Whether to always generate elements property even when there are no actual sub elements (applicable for non-compact output). |
ignoreDeclaration | false | Whether to ignore writing declaration property. That is, no declaration property will be generated. |
ignoreAttributes | false | Whether to ignore writing attributes of elements.That is, no attributes property will be generated. |
ignoreComment | false | Whether to ignore writing comments of the elements. That is, no comment will be generated. |
ignoreCdata | false | Whether to ignore writing CData of the elements. That is, no cdata will be generated. |
ignoreText | false | Whether to ignore writing texts of the elements. That is, no text will be generated. |
The below option is applicable only for xml2json()
function.
Option | Default | Description |
---|
spaces | 0 | Number of spaces to be used for indenting JSON output. |
Options for Changing Key Names
To change default key names in the output object or the default key names assumed in the input JavaScript object / JSON, use the following options:
Option | Default | Description |
---|
declarationKey | "declaration" or "_declaration" | Name of the property key which will be used for the declaration. For example, if declarationKey: '$declaration' then output of <?xml?> will be {"$declaration":{}} (in compact form) |
attributesKey | "attributes" or "_attributes" | Name of the property key which will be used for the attributes. For example, if attributesKey: '$attributes' then output of <a x="hello"/> will be {"a":{$attributes:{"x":"hello"}}} (in compact form) |
textKey | "text" or "_text" | Name of the property key which will be used for the text. For example, if textKey: '$text' then output of <a>hi</a> will be {"a":{"$text":"Hi"}} (in compact form) |
cdataKey | "cdata" or "_cdata" | Name of the property key which will be used for the cdata. For example, if cdataKey: '$cdata' then output of <![CDATA[1 is < 2]]> will be {"$cdata":"1 is < 2"} (in compact form) |
commentKey | "comment" or "_comment" | Name of the property key which will be used for the comment. For example, if commentKey: '$comment' then output of <!--note--> will be {"$comment":"note"} (in compact form) |
parentKey | "parent" or "_parent" | Name of the property key which will be used for the parent. For example, if parentKey: '$parent' then output of <a></b></a> will be {"a":{"b":{$parent:_points_to_a}}} (in compact form) |
typeKey | "type" | Name of the property key which will be used for the type. For example, if typeKey: '$type' then output of <a></a> will be {"elements":[{"$type":"element","name":"a","attributes":{}}]} (in non-compact form) |
nameKey | "name" | Name of the property key which will be used for the name. For example, if nameKey: '$name' then output of <a></a> will be {"elements":[{"type":"element","$name":"a","attributes":{}}]} (in non-compact form) |
elementsKey | "elements" | Name of the property key which will be used for the elements. For example, if elementsKey: '$elements' then output of <a></a> will be {"$elements":[{"type":"element","name":"a","attributes":{}}]} (in non-compact form) |
TIP: You probably want to set {textKey: 'value', cdataKey: 'value', commentKey: 'value'}
for non-compact output
to make it more consistent and easier for your client code to go through the contents of text, cdata, and comment.
Command Line
Because any good library should support command line usage, this library is no difference.
As Globally Accessible Command
npm install -g xml-js // install this library globally
xml-js test.json --space 4 // xml result will be printed on screen
xml-js test.json --space 4 --out test.xml // xml result will be saved to test.xml
xml-js test.xml --space 4 // json result will be printed on screen
xml-js test.xml --space 4 --out test.json // json result will be saved to test.json
As Locally Accessible Command
If you want to use it as script in package.json (can also be helpful in task automation via npm scripts)
npm install --save xml-js // no need to install this library globally
In package.json, write a script:
...
"dependencies": {
"xml-js": "latest"
},
"scripts": {
"convert": "xml-js test.json --spaces 4"
}
npm run convert // task 'scripts.convert' will be executed
CLI Arguments
Usage: xml-js src [options]
src Input file that need to be converted.
Conversion type xml->json or json->xml will be inferred from file extension.
Options:
--help, -h Display this help content.
--version, -v Display number of this module.
--out Output file where result should be written.
--spaces Specifies amount of space indentation in the output.
--full-tag XML elements will always be in <a></a> form.
--no-decl Declaration instruction <?xml ..?> will be ignored.
--no-attr Attributes of elements will be ignored.
--no-text Texts of elements will be ignored.
--no-cdata Cdata of elements will be ignored.
--no-comment Comments of elements will be ignored.
--trim Whitespaces surrounding texts will be trimmed.
--compact JSON is in compact form.
--sanitize Special xml characters will be replaced with entity codes.
--native-type Numbers and boolean will be converted (coreced) to native type instead of text.
--always-children Every element will always contain sub-elements (applicable if --compact is not set).
--text-key To change the default 'text' key.
--cdata-key To change the default 'cdata' key.
--comment-key To change the default 'comment' key.
--attributes-key To change the default 'attributes' key.
--declaration-key To change the default 'declaration' key.
--type-key To change the default 'type' key (applicable if --compact is not set).
--name-key To change the default 'name' key (applicable if --compact is not set).
--elements-key To change the default 'elements' key (applicable if --compact is not set).
Contribution
Comparison with Other Libraries
xml2js
xml2json
xml-objects
xml-js-converter
fast-xml2js
co-xml2js
xml-simple
xml2js-expat
Testing
To perform tests on this project:
cd node_modules/xml-js
npm install
npm test
For live testing, use npm start
instead of npm test
.
Reporting
Use this link to report an issue or bug. Please include a sample code where the code is failing.
License
MIT