avoiding callback pyramids

dbVerify.js

#!/usr/bin/env node

'use strict'

var mysql = require('mysql')
var fs = require('fs')
var path = require('path')

function exitOnError (f) {
  return function (err) {
    if (err) {
      console.error(err)
      process.exit(1)
    }
    f && f.apply(this, arguments)
  }
}

function main (args) {
  var url = args[0]
  console.log(url)

  var connection = mysql.createConnection({
    host: process.env.MYSQL_HOST || 'localhost', //
    user: process.env.MYSQL_USER || 'root', // these should be
    password: process.env.MYSQL_PASSWORD || '', // default install settings
    database: process.env.MYSQL_DATABASE || 'information_schema'
  })

  connection.connect(exitOnError(onConnect))

  function onConnect () {
    // setup test user for password test
    var sql = fs.readFileSync(path.resolve(__dirname, 'create_user.sql'), { encoding: 'utf8' })
    connection.query(sql, exitOnError(onQuery))
  }

  function onQuery () {
    connection.end(exitOnError())
  }
}

if (require.main === module) {
  main(process.argv.slice(2))
}