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.

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

Type definitions are maintained at DefinitelyTyped by others. You can install them with:

npm install --dev @types/web3.js

You might need to install type definitions for bignumber.js and lodash too.

And then use web3.js as follows:

import Web3 = require("web3"); // Note the special syntax! Copy this line when in doubt!
const web3 = new Web3("ws://localhost:8546");

Please note: We do not support TypeScript ourselves. If you have any issue with TypeScript and web3.js do not create an issue here. Go over to DefinitelyTyped and do it there.

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

• All contributions have to go into develop, or the 1.0 branch
• Please follow the code style of the other files, we use 4 spaces as tabs.

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