What is cids?
The 'cids' npm package is used for handling Content Identifiers (CIDs) in the context of IPFS (InterPlanetary File System). CIDs are a fundamental part of IPFS, allowing for unique identification of content based on its cryptographic hash. This package provides utilities for creating, parsing, and working with CIDs.
What are cids's main functionalities?
Creating a CID
This feature allows you to create a new CID instance. The constructor takes the version, codec, and multihash as parameters. The example demonstrates creating a CID of version 1 with the 'dag-pb' codec.
const CID = require('cids');
const cid = new CID(1, 'dag-pb', Buffer.from('1220...'));
console.log(cid.toString());
Parsing a CID
This feature allows you to parse an existing CID string. The example shows how to parse a CID and access its version property.
const CID = require('cids');
const cid = new CID('Qm...');
console.log(cid.version);
Converting CID to different formats
This feature allows you to convert a CID to different versions. The example demonstrates converting a CID to version 1 and then converting it to a string.
const CID = require('cids');
const cid = new CID('Qm...');
console.log(cid.toV1().toString());
Other packages similar to cids
multihashes
The 'multihashes' package provides utilities for working with multihashes, which are a key component of CIDs. While 'cids' focuses on the entire CID structure, 'multihashes' is more specialized in handling the multihash part of CIDs.
multibase
The 'multibase' package is used for encoding and decoding data in various base encodings. CIDs often use multibase for encoding their string representations. This package is more focused on the encoding aspect, whereas 'cids' handles the entire CID structure.
ipld
The 'ipld' package provides tools for working with InterPlanetary Linked Data (IPLD), which is the data model used by IPFS. While 'cids' is specifically for handling CIDs, 'ipld' provides a broader set of tools for working with the data structures that CIDs point to.
js-cid
CID implementation in JavaScript.
Lead Maintainer
Volker Mische
Table of Contents
Install
In Node.js through npm
$ npm install --save cids
Browser: Browserify, Webpack, other bundlers
The code published to npm that gets loaded on require is in fact an 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.
const CID = require('cids')
In the Browser through <script>
tag
Loading this module through a script tag will make the Cids
obj available in the global namespace.
<script src="https://unpkg.com/cids/dist/index.min.js"></script>
<!-- OR -->
<script src="https://unpkg.com/cids/dist/index.js"></script>
Gotchas
You will need to use Node.js Buffer
API compatible, if you are running inside the browser, you can access it by multihash.Buffer
or you can install Feross's Buffer.
Usage
Basic usage is quite simple.
const CID = require('cids')
const cid = new CID(1, 'dag-pb', multihash)
If you have a base encoded string for a multihash you can also create
an instance from the encoded string.
const cid = new CID(base58Multihash)
API
CID.isCID(cid)
Returns true if object is a valid CID instance, false if not valid.
It's important to use this method rather than instanceof
checks in
order to handle CID objects from different versions of this module.
CID.validateCID(cid)
Validates the different components (version, codec, multihash) of the CID
instance. Returns true if valid, false if not valid.
new CID(version, codec, multihash)
version
must be either 0 or 1.
codec
must be a string of a valid registered codec.
multihash
must be a Buffer
instance of a valid multihash.
new CID(baseEncodedString)
Additionally, you can instantiate an instance from a base encoded
string.
new CID(Buffer)
Additionally, you can instantiate an instance from a buffer.
cid.codec
Property containing the codec string.
cid.version
Property containing the CID version integer.
cid.multihash
Property containing the multihash buffer.
cid.buffer
Property containing the full CID encoded as a Buffer
.
cid.prefix
Proprety containing a buffer of the CID version, codec, and the prefix
section of the multihash.
cid.toV0()
Returns the CID encoded in version 0. Only works for dag-pb
codecs.
Throws if codec is not dag-pb
.
cid.toV1()
Returns the CID encoded in version 1.
cid.toBaseEncodedString(base='base58btc')
Returns a base encodec string of the CID. Defaults to base58btc
.
cid.equals(cid)
Compare cid instance. Returns true if CID's are identical, false if
otherwise.
Contribute
Contributions welcome. Please check out the issues.
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 multiformats are subject to the IPFS Code of Conduct.
Small note: If editing the Readme, please conform to the standard-readme specification.
License
MIT