gozala / js-ipld-dag-cbor

JavaScript implementation of the IPLD dag-cbor format.

js-ipld-dag-cbor

JavaScript implementation of the IPLD spec.

Lead Maintainer

Volker Mische

Table of Contents

• Install
  • npm
  • Use in Node.js
  • Use in a browser with browserify, webpack or any other bundler
  • Use in a browser Using a script tag
• Usage
• API
• Contribute
• License

Install

npm

> npm install ipld-dag-cbor

Use in Node.js

const dagCBOR = require('ipld-dag-cbor')

Use in a browser with browserify, webpack or any other bundler

The code published to npm that gets loaded on require is in fact a ES5 transpiled version with the right shims added. This means that you can require it and use with your favourite bundler without having to adjust asset management process.

var dagCBOR = require('ipld-dag-cbor')

Use in a browser Using a script tag

Loading this module through a script tag will make the IpldDagCbor obj available in the global namespace.

<script src="https://unpkg.com/ipld-dag-cbor/dist/index.min.js"></script>
<!-- OR -->
<script src="https://unpkg.com/ipld-dag-cbor/dist/index.js"></script>

Usage

const dagCBOR = require('ipld-dag-cbor')

const file = {
  name: 'hello.txt',
  size: 11
}

const serialized = dagCBOR.util.serialize(file)
console.log(`Encoded as a ${serialized.length} byte Buffer`)

const node = dagCBOR.util.deserialize(serialized)
console.log('Decoded as:', node)
require('assert').deepEqual(node, file) // should match

// → Encoded as a 22 byte Buffer
// → Decoded as: { name: 'hello.txt', size: 11 }

API

dagCBOR.util.serialize(obj)

Encodes an object into IPLD CBOR form, replacing any CIDs found within the object to CBOR tags (with an id of 42).

• obj (any): any object able to be serialized as CBOR

Returns the serialized node.

dagCBOR.util.deserialize(serialized)

Decodes an IPLD CBOR encoded representation, restoring any CBOR tags (id 42) to CIDs.

• serialized (Buffer or String): a binary blob representing an IPLD CBOR encoded object.

Returns the deserialized object.

dagCBOR.util.configureDecoder([options])

Configure the underlying CBOR decoder.

Possible values in the options argument are:

• size (Number, optional): the current heap size used in CBOR parsing, this may grow automatically as larger blocks are encountered up to maxSize. Default: 65536 (64Kb).
• maxSize (Number, optional): the maximum size the CBOR parsing heap is allowed to grow to before dagCBOR.util.deserialize() returns an error. Default: 67108864 (64Mb).
• tags (Object, optional): an object whose keys are CBOR tag numbers and values are transform functions that accept a value and return a decoded representation of that value.

The CBOR decoder uses a heap size that is a power of two. Setting size to a number other than a power of two will result in a heap using the next-largest power of two.

Calling dagCBOR.util.configureDecoder() with no arguments will reset to the default decoder size, maxSize and tags.

dagCBOR.util.cid(obj[, options,])

Create a CID for the given unserialized object.

• obj (any): any object able to be serialized as CBOR
• options (Object):

• hashAlg (String): a registered multicodec hash algorithm.
• hashLen (String): an optional hash length
• version (Number): CID version number, defaults to 1

Returns a Promise with the created CID.

Contribute

Feel free to join in. All welcome. Open an issue!

Check out our contributing document for more information on how we work, and about contributing in general. Please be aware that all interactions related to IPLD are subject to the IPFS Code of Conduct.

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

License

MIT © 2015 David Dias