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Test GitHub package version NPM package name standard-readme compliant

Tools for working with the JSKOS data format.

This repository contains tools for working with the JSKOS data format for knowledge organization systems.

Table of Contents


npm i jskos-tools

We are also providing browser bundles:


If you installed jskos-tools via npm, use it like this:

const jskos = require("jskos-tools")

Using the browser bundles will provide you with the jskos global variable.

See for full API documentation of module jskos-tools.

Mapping Identifiers

let mapping = {


mappingContentIdentifier starts with urn:jskos:mapping:content: and takes concepts and type into consideration. It uses the mappingContent function to get relevant properties from the mapping.

let contentIdentifier = jskos.mappingContentIdentifier(mapping)


mappingMembersIdentifier starts with urn:jskos:mapping:members: and only takes concepts into consideration. It uses the mappingMembers function to get relevant properties from the mapping.

let membersIdentifier = jskos.mappingMembersIdentifier(mapping)


addMappingIdentifiers creates a new mapping with property "identifiers", containing mappingContentIdentifier and mappingMembersIdentifier.

let mappingWithIdentifiers = jskos.addMappingIdentifiers(mapping)


compareMappings compares two mappings based on their mappingContentIdentifier.

if (jskos.compareMappings(mapping1, mapping2)) { ... }

Aliases: compareMappingContent


compareMappingMembers compares two mappings based on their mappingMembersIdentifier.

if (jskos.compareMappingMembers(mapping1, mapping2)) { ... }


See class ConceptScheme.


Used to provide access to a preference list of language tags.

How to Configure

If this is used inside a web application that allows multiple interface languages and depends on reactivity, it is necessary to properly configure this at the start of the application. There are two ways to do this:

  1. Provide a reference to the Vuex store and path where the language preference list of the application resides:
const store = require("./store") // import the Vuex store = store
jskos.languagePreference.path = "state.languages" // or wherever your languages array resides

Note: In theory, store doesn't HAVE to be a Vuex store. It could be any kind of object which contains the languages array somewhere. (See also: Tests)

  1. Provide a reference to a preference list array of languages tags directly via defaults. Note: Make sure that this array only gets modified in-place, otherwise you will override the previous reference to the array. (Example using array.prototype.move.)
const languages = ["en", "de"]
jskos.languagePreference.defaults = languages
languages.move(1, 0) // moves "de" to the front of the preference list


Returns the current preference list of language tags (either from store or defaults).


Selects a language tag from a language map according to the current preference list or null if no language was found.



Add @context URI to a JSKOS object or to an array of JSKOS objects.



Removes properties starting with _ or containing only uppercase letters from a JSKOS object.


Aliases: cleanJSKOS


Creates a deep copy of a JSKOS object, replacing possibly circular structures with open world [null] statements. As the second argument it is possible to add additional properties that should be replaced with open world [null] statements. The third argument determines whether all properties starting with _ should be ignored (true by default).

jskos.copyDeep(object, ["someCircularProperty"])
jskos.copyDeep(object, null, false)

Aliases: deepCopy


Returns all possible URIs for a JSKOS object. Takes into consideration both the uri and identifier properties, as well as different variants of those identifiers. Returns an empty array if object is null.



Compares two objects based on their URIs, using getAllUris. Returns true if both objects are null., object2)

Aliases: compareObjects, compareSchemes, compareConcepts


Checks whether JSKOS object is a concept based on type property.



Checks whether JSKOS object is a concept scheme based on type property.



// Checks whether an object is contained in a list of objects using compare.

jskos.isContainedIn(object, listOfObjects)

Aliases: isSchemeInList


Sorts a list of concepts by their notation, then URI. Returns a copy of the list. If the second parameter is true, it will try to sort by numerical notations.



Sorts a list of schemes by their prefLabel (de or en), then notation, then URI. Returns a copy of the list.



Removes unnecessary properties from mapping before export or saving. In particular, all properties except for to, from, toScheme, fromScheme, type, creator, contributor, created, modified, note, and identifier on the mapping will be removed, and all properties except for uri and notation on concepts and schemes will be removed.

let newMapping = jskos.minifyMapping(mapping)


An array of mapping types in form of objects. Objects can have the following properties:

  • notation - an array of notations (in this case symbols)
  • uri - the URI of the mapping type
  • prefLabel - a language maps of labels
  • broader - array of broader mapping types for this type
  • related - array of related mapping types
  • RELEVANCE - relevance label for GND terms (low, medium, high, very high)
  • SHORT - a short name for the type, used for CSV import/export

The labels are taken from Wikidata (see script bin/localize-mapping-types).

Example object:

  "notation": [""],
  "uri": "",
  "prefLabel": { "en": "close match" },
  "broader": [ { "uri": "" } ],
  "RELEVANCE": "high",
  "SHORT": "close"


Returns a mapping type object for an URI.



Returns a mapping type for a JSKOS type property. This is usually an array where the first type is taken, but a workaround for string types is included as well.



The default mapping type (currently mapping relation).


Converts a mapping into a flat object with for serialization as CSV. Returns an object with fields fromNotation, toNotation, type, and (if option language has been provided) fromLabel, toLabel, and creator.


Returns an object of preconfigured conversion functions to convert mappings into CSV. Supports 1-to-1, 1-to-n, and n-to-n mappings.

// Initialize converter with default options
const csv = jskos.mappingCSV({
  delimiter: ",",
  quoteChar: "\"",
  lineTerminator: "\n",
  type: true,
  schemes: false,
  labels: false,
  creator: false,
  language: "en",
// Header line for an array of mappings (assuming 1-to-1 mappings if no array is given)
// Single CSV line for a mapping (uses fromCount and toCount from the mapping by default)
csv.fromMapping(mapping, { fromCount: null, toCount: null })
// Multiline CSV from array of mappings (includes header by default)
csv.fromMappings(mappings, { header: true })

The order of the CSV fields is fromScheme, fromNotation, (fromLabel,) (fromNotation2, fromLabel2, ...) toNotation, (toLabel,) (toNotation2, toLabel2, ...) type, creator.


Returns a function to serialize an array as CSV row as configured with CSV Dialect.


Returns an array of concepts contained in a mapping. side can either be from or to. If side is left out, concepts from both sides will be returned. null values will be omitted.



compareMappingsDeep compares two mappings based on their properties. Concept sets and schemes are compared by URI.

if (jskos.compareMappingsDeep(mapping1, mapping2)) { ... }


Compares two JSKOS objects based on their types. Returns false only if both types could be guessed using guessObjectType and they did not match, otherwise it will assume that the types match.


Merge URIs of two objects a and b into a by adding/removing URIs from identifier property.


Merges two JSKOS objects. See documentation for more information.


Applies recursive unicode normalization to data.


Checks whether a string is a valid URI.


An object that maps JSKOS object type names to their description.


Guess the JSKOS object type of an object, URI or name and return its canonical name.

type = guessObjectType(objectOrString)        // get full name such as `ConceptScheme`
type = guessObjectType(objectOrString, true)  // get short name such as `scheme`


Filter a list of concept schemes with a given notation to guess which scheme(s) the notation origins from. Schemes without notationPattern or default pattern .+ are ignored. Returns a (posssibly empty) array of concept schemes.

matchingSchemes = guessSchemeFromNotation(notation, schemes)


An object containing compare functions that can be used with array.sort() etc.

Available functions:

  • compareFunctions.mappingsByConcepts - compares mappings by the notations of their first concepts


Determines whether a (login-server-compatible) user owns a mapping (i.e. is the first creator) or not.


Returns the primary notation for a JSKOS Item. If there is no notation, it will return an empty string. Scheme notations will be uppercased.


Returns the content of a language map for a JSKOS Item.


Returns the prefLabel of a JSKOS Item. If there is no label, it will return the URI. If there is no URI, it will return an empty string.


Returns the definition of a JSKOS Item as an array. If there is no definition, an empty array will be returned.


Returns whether a mapping registry has stored mappings (true = database) or not (false = recommendations).


Returns the creator URI for an annotation.


Returns the craetor name for an annotation.


Matches an annotation's creator URI against a list of URIs (e.g. from a user).


git clone --recursive
cd jskos-tools/
npm install

API documentation can be generated in directory jsdoc/build:

npm run docs


npm test



Please work on the dev branch during development (or better yet, develop in a feature branch and merge into dev when ready).

When a new release is ready (i.e. the features are finished, merged into dev, and all tests succeed), run the included release script (replace "patch" with "minor" or "major" if necessary):

npm run release:patch

This will:

  • Run tests and build to make sure everything works
  • Switch to dev
  • Make sure dev is up-to-date
  • Run npm version patch (or "minor"/"major")
  • Push changes to dev
  • Switch to master
  • Merge changes from dev
  • Push master with tags
  • Switch back to dev

After running this, GitHub Actions will automatically publish the new version to npm. It will also create a new GitHub Release draft. Please edit and publish the release manually.


PRs accepted.

Small note: If editing the README, please conform to the standard-readme specification.


MIT © 2018 Verbundzentrale des GBV (VZG)