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

Meteor

Note: works only in the Browser for now. (PR welcome).

meteor add ethereum: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 read the docs.

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
• Forum

Similar libraries in other languages

• Python - Web3.py
• Haskell - hs-web3
• Java - web3j
• Scala - web3j-scala
• Purescript - purescript-web3
• PHP - web3.php
• Ruby - ethereum.rb