Listen to new blocks

This example shows how to subscribe to new blocks.

It displays the block number every time a new block is seen by the node you are connected to.

NOTE: The example runs until you stop it with CTRL+C

// Import the API
const { ApiPromise } = require('@polkadot/api');
const { typesBundleForPolkadot } = require('@crustio/type-definitions');
async function main () {
// Here we don't pass the (optional) provider, connecting directly to the default
// node/port, i.e. `ws://`. Await for the isReady promise to ensure
// the API has connected to the node and completed the initialisation process
const api = await ApiPromise.create({
provider: new WsProvider('ws://'),
typesBundle: typesBundleForPolkadot
// We only display a couple, then unsubscribe
let count = 0;
// Subscribe to the new headers on-chain. The callback is fired when new headers
// are found, the call itself returns a promise with a subscription that can be
// used to unsubscribe from the newHead subscription
const unsubscribe = await api.rpc.chain.subscribeNewHeads((header) => {
console.log(`Chain is at block: #${header.number}`);
if (++count === 256) {