const Web3 = require('web3');

const url = 'https://rpc.ankr.com/eth/b6d15c9349c08c6cb163ea23a6e0cc7d94664381ff63381f5e37f6c04109e26d'  // url string

const web3 = new Web3(new Web3.providers.HttpProvider(url));

web3.eth.getBlockNumber((error, blockNumber) => {
    if(!error) {
        console.log(blockNumber);
    } else {
        console.log(error);
    });