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
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
Similar libraries in other languages
- Python - Web3.py
- Haskell - hs-web3
- Java - web3j
- Scala - web3j-scala
- Purescript - purescript-web3
- PHP - web3.php