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 web3

Yarn

yarn add web3

In the Browser

Use the prebuilt dist/web3.min.js, or build using the web3.js repository:

npm run build

Then 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: angular/angular-cli#1548

Documentation

Documentation can be found at ReadTheDocs.

Building

Requirements

Node.js
npm

sudo apt-get update
sudo apt-get install nodejs
sudo apt-get install npm

Building (webpack)

Build the web3.js package:

npm run build

Testing (mocha)

npm test

Contributing

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

wackerow / web3.js