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

npm run-script build

Then include dist/web3.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
var Web3 = require('web3');

var 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 for example a node app you just have to enable esModuleInterop in your tsconfig compile option, also enable allowSyntheticDefaultImports 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 (gulp)

Build only the web3.js package:

npm run-script build

Or build all sub packages as well:

npm run-script build-all

This will put all the browser build files into the dist folder.

Testing (mocha)

npm test

Contributing

The contribution guidelines are provided in CONTRIBUTIONS

Community

• Gitter
• StackExchange
• Forum

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