Template to setup subproviders and Web3

subprovider-setup.js

const MnemonicWalletSubprovider = require('@0xproject/subproviders').MnemonicWalletSubprovider
const RPCSubprovider = require('web3-provider-engine/subproviders/rpc')
const Web3ProviderEngine = require('web3-provider-engine')
const Web3Wrapper = require('@0xproject/web3-wrapper').Web3Wrapper
const Web3 = require('web3')
const fs = require('fs')

const NETWORK_ID = 1
const INFURA_API_KEY = '<INFURA_API_KEY>'
const MNEMONIC = fs.readFileSync('./mnemonic.txt', 'utf8')

const networkNames = new Map([
    [ 1, 'mainnet' ],
    [ 3, 'ropsten' ],
    [ 4, 'rinkeby' ],
    [ 42, 'kovan' ]
]);


const mnemonicWalletSubprovider = new MnemonicWalletSubprovider({ mnemonic: MNEMONIC})
//const injectedWeb3Subprovider = new InjectedWeb3Subprovider(window.web3.currentProvider) // for browser
const localRpcSubprovider = new RPCSubprovider({
    rpcUrl: 'http://localhost:8545'
})
const infuraRpcSubprovider = new RPCSubprovider({
    rpcUrl: 'https://' + networkNames.get(NETWORK_ID) + '.infura.io/' + INFURA_API_KEY
})

const providerEngine = new Web3ProviderEngine()
providerEngine.addProvider(mnemonicWalletSubprovider)
providerEngine.addProvider(infuraRpcSubprovider)
providerEngine.start();

const web3Wrapper = new Web3Wrapper(providerEngine)
const web3 = new Web3(providerEngine)

const init = async () => {
    console.log('Using network ' + networkNames.get(NETWORK_ID))
    console.log('Running with Mnemonic path: ' + mnemonicWalletSubprovider.getPath())
    const accounts = await mnemonicWalletSubprovider.getAccountsAsync(3)
    console.log('Accounts: ')
    for (account of accounts) {
        console.log('       ' + account)
    }
    console.log('-------------------------------------------------------')
}
// Use web3/web3Wrapper here...