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 wit CTRL+C

const BN = require('bn.js')
const Api = require('@polkadot/api').default
const WsProvider = require('@polkadot/api-provider/ws').default
const provider = new WsProvider('ws://127.0.0.1:9944')
const api = new Api(provider)

function main () {
  console.log('Blocks will be shown as they come in, CTRL+C to stop:')
  api.chain.newHead((_, header) => {
    const bnBlockNumber = new BN(header.number, 16)

    console.log('#' + bnBlockNumber.toString(10))
  })
}

main()