web3.js - Ethereum JavaScript API
This is the Ethereum JavaScript API which connects to the Generic JSON-RPC spec.
You need to run a local or remote Ethereum node to use this library.
Please read the documentation for more.
Installation
Node
npm install web3Yarn
yarn add web3In the Browser
Use the prebuilt dist/web3.min.js, or
build using the web3.js repository:
npm run buildThen include dist/web3.min.js in your html file.
This will expose Web3 on the window object.
Or via jsDelivr CDN:
<script src="https://cdn.jsdelivr.net/npm/web3@latest/dist/web3.min.js"></script>UNPKG:
<script src="https://unpkg.com/web3@latest/dist/web3.min.js"></script>Usage
// In Node.js
const Web3 = require('web3');
let web3 = new Web3('ws://localhost:8546');
console.log(web3);
> {
eth: ... ,
shh: ... ,
utils: ...,
...
}Additionally you can set a provider using web3.setProvider() (e.g. WebsocketProvider):
web3.setProvider('ws://localhost:8546');
// or
web3.setProvider(new Web3.providers.WebsocketProvider('ws://localhost:8546'));There you go, now you can use it:
web3.eth.getAccounts().then(console.log);Usage with TypeScript
We support types within the repo itself. Please open an issue here if you find any wrong types.
You can use web3.js as follows:
import Web3 from 'web3';
const web3 = new Web3('ws://localhost:8546');If you are using the types in a commonjs module, like in a Node app, you just have to enable esModuleInterop and allowSyntheticDefaultImports in your tsconfig for typesystem compatibility:
"compilerOptions": {
"allowSyntheticDefaultImports": true,
"esModuleInterop": true,
....Trouble shooting and known issues.
Web3 and Angular
If you are using Ionic/Angular at a version >5 you may run into a build error in which modules crypto and stream are undefined
a work around for this is to go into your node-modules and at /angular-cli-files/models/webpack-configs/browser.js change the node: false to node: {crypto: true, stream: true} as mentioned here
Another variation of this problem was an issue opned on angular-cli: https://github.com/angular/angular-cli/issues/1548
Documentation
Documentation can be found at ReadTheDocs.
Building
Requirements
sudo apt-get update
sudo apt-get install nodejs
sudo apt-get install npmBuilding (webpack)
Build the web3.js package:
npm run buildTesting (mocha)
npm testContributing
Please follow the Contribution Guidelines and Review Guidelines.
This project adheres to the Release Guidelines.
Community
Similar libraries in other languages
- Haskell: hs-web3
- Java: web3j
- PHP: web3.php
- Purescript: purescript-web3
- Python: Web3.py
- Ruby: ethereum.rb
- Scala: web3j-scala
Semantic versioning
This project follows semver as closely as possible from version 1.3.0 onwards. Earlier minor version bumps might have included breaking behavior changes.
