#!/usr/bin/env node
const Web3 = require('web3');

const web3 = new Web3(new Web3.providers.WebsocketProvider('wss://mainnet.infura.io/ws'));

const subscription = web3.eth.subscribe('newBlockHeaders', (error, blockHeader) => {
  if (error) return console.error(error);

  console.log('Successfully subscribed!', blockHeader);
}).on('data', (blockHeader) => {
  console.log('data: ', blockHeader);
});

// unsubscribes the subscription
subscription.unsubscribe((error, success) => {
  if (error) return console.error(error);

  console.log('Successfully unsubscribed!');
});