electrum-cash

electrum-cash

Electrum-cash is a lightweight JavaScript library that lets you connect with one or more Electrum servers. It offers encrypted connections by default, performs the expected protocol version negotiation and automatically keeps your connection alive until your close it.

Installation

Install the library with NPM:

# npm install electrum-cash

Usage

Load library

Before you can use the library you need to include it in your project.

If you only want to use a single server, load the ElectrumClient module:

// Load the electrum library.
const { ElectrumClient } = require('electrum-cash');

If you want to use multiple servers, load the ElectrumCluster module:

// Load the electrum library.
const { ElectrumCluster } = require('electrum-cash');

Connect to servers

After you have loaded the appropriate module you need to initialize the module by configuring your application identifier and protocol version.

If you only want to use a single server, initialize an ElectrumClient and connect to the server:

// Initialize an electrum client.
const electrum = new ElectrumClient('Electrum client example', '1.4.1', 'bch.imaginary.cash');

// Wait for the client to connect
await electrum.connect();

If you want to use multiple servers, initialize an ElectrumCluster and add some servers:

For more information on various cluster configurations, read the cluster documentation.

// Initialize an electrum cluster where 2 out of 3 needs to be consistent, polled randomly with fail-over (default).
const electrum = new ElectrumCluster('Electrum cluster example', '1.4.1', 2, 3);

// Add some servers to the cluster.
electrum.addServer('bch.imaginary.cash');
electrum.addServer('electroncash.de');
electrum.addServer('electroncash.dk');
electrum.addServer('electron.jochen-hoenicke.de', 51002);
electrum.addServer('electrum.imaginary.cash');

// Wait for enough connections to be available.
await electrum.ready();

Request information

Once your ElectrumClient or ElectrumCluster is connected and ready, you can call methods:

For a list of methods you can use, refer to the Electrum Cash documentation.

// Declare an example transaction ID.
const transactionID = '4db095f34d632a4daf942142c291f1f2abb5ba2e1ccac919d85bdc2f671fb251';

// Request the full transaction hex for the transaction ID.
const transactionHex = await electrum.request('blockchain.transaction.get', transactionID);

// Print out the transaction hex.
console.log(transactionHex);

Subscribe to notifications.

Once your ElectrumClient or ElectrumCluster is connected and ready, you can set up subscriptions to get notifications on events:

For a list of methods you can subscribe to, refer to the Electrum Cash documentation.

// Set up a callback function to handle new blocks.
const handleNotifications = function(data)
{
	if(data.method === 'blockchain.headers.subscribe')
	{
		// Print out the block information.
		// {
		// 	jsonrpc: '2.0',
		// 	method: 'blockchain.headers.subscribe',
		// 	params:
		// 	[
		// 		{
		// 		height: 797111,
		// 		hex: '002001202a6b1367f68201ad957e95bec9bda3f132ca2fcb75c0c000000000000000000074befba60bd8615d87ddb636aa99bc032cec8db3adb0d915d45391bc811c1e9ceacf89647a60051819a79559'
		// 		}
		// 	]
		// }
		console.log(data);
	}
}

// Listen for notifications.
electrum.on('notification', handleNotifications);

// Set up a subscription for new block headers.
await electrum.subscribe('blockchain.headers.subscribe');

Shutting down

When you're done and don't want to be connected anymore you can disconnect the server(s).

If you're using a single ElectrumClient, call the disconnect() function:

// Close the connection.
await electrum.disconnect();

If you're using a ElectrumCluster with multiple servers, call the shutdown() function.

// Close all connections.
await electrum.shutdown();

Documentation

For a complete list of methods and parameters, read the API documentation.

Support and communication

If you need help with how to use the library or just want to talk about electrum-cash, you can find us on Telegram and Discord.

You can also read our tutorials on read.cash, or share your own.

Notes

The keep-alive functionality of this library only works when the protocol version is 1.2 or higher.