edn-data

edn-data is a JavaScript and TypeScript library that provides functionality to generate and parse data in the EDN format, as known from Clojure land.

Why create another library for working with EDN?

• Support TypeScript with a strictly typed interface
• Support the rich EDN types
• Allow working with plain data in JavaScript, so everything can also be serialized to JSON
• Support modern JavaScript types such as Map, Set and bigint
• Support streaming EDN lists as standard Node stream in Node.js
• Have a solution that works in Node.js and in browsers

Why work with EDN in JavaScript or TypeScript?

The number one reason is, your code wants to interact with data coming from Clojure.

But even outside Clojure EDN can be a compelling data format in a world where developers are stuck fighting YAML and complaining about JSON.

EDN has:

• less syntax than JSON
• built-in data types to represent maps, sets, keywords, dates, uuids, chars, bigints, ...
• multi-line strings
• tags and symbols to represent rich, custom data types
• comments
• streaming parsers
• no relevant whitespace

Get started

Install with:

npm install edn-data

Parsing EDN

By default parsing returns JSON-compatible data structures that can represent all of the rich EDN types.

There are options to make it easier to parse simpler types.

import { parseEDNString } from 'edn-data'

parseEDNString('{:key "value" :list [1 2 3]}')
// Returns:
{
  map: [
    [{ key: 'key' }, 'value'],
    [{ key: 'list' }, [1, 2, 3]],
  ],
}

parseEDNString(
  '{:key "value" :list [1 2 3]}',
  { mapAs: 'object', keywordAs: 'string' },
)
// Returns:
{
  key: 'value',
  list: [1, 2, 3],
}

EDN lists can be streamed value by value as standard Node.js Readable streams. This is not available in the browser.

import { parseEDNListStream } from 'edn-data/stream'

const s = parseEDNListStream()
s.write('(1 2 3)')
s.read() // 1
s.read() // 2
s.read() // 3

Generating EDN

EDN is generated from plain JSON structures.

With toEDNString the same data structures parseEDNString returns can be turned to valid strings, and they represent a rich set of types.

For simple JavaScript types often toEDNStringFromSimpleObject might be the simpler use.

import { toEDNString, toEDNStringFromSimpleObject } from 'edn-data';

toEDNString({
  map: [
    [1, { key: 'keyword' }],
    [{ set: [1, 2] }, { char: 'a' }],
  ],
})
// Returns:
'{1 :keyword #{1 2} \a}'

toEDNStringFromSimpleObject({ first: 1, second: 2 })
// Returns:
'{:first 1 :second 2}'

Development

The library is developed driven by its tests.

Verify them using

npm test

For continuous development use

npm run test:watch

Ensure the code formatting with

npm run fix

CI verifies tests and creates npm releases for tags automatically.

Publish a new version

1. Change the version in the package.json
2. Run npm install to make sure the package-lock.json file is up to date
3. Push a commit to master in the following form Release <version>
4. A Git tag will be created and the new version will be published to NPM

License

MIT