@ipld/dag-cbor

@ipld/dag-cbor

JS implementation of DAG-CBOR

Table of contents

• Install
• Spec
• License
• Contribute

Install

$ npm i @ipld/dag-cbor

This is the new interface meant for use by itself or with multiformats and @ipld/block. It is not used by js-ipld-format which is currently used in IPFS. That library is here.

Usage:

import { encode, decode } from '@ipld/dag-cbor'
import { CID } from 'multiformats'

const obj = {
  x: 1,
  /* CID instances are encoded as links */
  y: [2, 3, CID.parse('QmaozNR7DZHQK1ZcU9p7QdrshMvXqWK6gpu5rmrkPdT3L4')],
  z: {
    a: CID.parse('QmaozNR7DZHQK1ZcU9p7QdrshMvXqWK6gpu5rmrkPdT3L4'),
    b: null,
    c: 'string'
  }
}

let data = encode(obj)
let decoded = decode(data)
decoded.y[0] // 2
CID.asCID(decoded.z.a) // cid instance

// encode/decode options are exported for use with cborg's encodedLength and decodeFirst
import { encodeOptions, decodeOptions } from '@ipld/dag-cbor'
import { encodedLength } from 'cborg/length'
import { decodeFirst } from 'cborg'

// dag-cbor encoded length of obj in bytes
const byteLength = encodedLength(obj, encodeOptions)
byteLength // 104

// concatenate two dag-cbor encoded obj
const concatenatedData = new Uint8Array(data.length * 2)
concatenatedData.set(data)
concatenatedData.set(data, data.length)

// returns dag-cbor decoded obj at the beginning of the buffer as well as the remaining bytes
const [first, remainder] = decodeFirst(concatenatedData, decodeOptions)
assert.deepStrictEqual(first, obj)
assert.deepStrictEqual(remainder, data)

Spec

The dag-cbor specification is in the IPLD specs repo.

License

Licensed under either of

• Apache 2.0, (LICENSE-APACHE / http://www.apache.org/licenses/LICENSE-2.0)
• MIT (LICENSE-MIT / http://opensource.org/licenses/MIT)

Contribute

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.