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,
    ....

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

• Gitter
• StackExchange

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