logo-server.js

const express = require('express')
const get = require('lodash.get')
const keyBy = require('lodash.keyBy')

/**
 * Initializes express application
 * You should include whatever middleware you need here (cors, etc.)
 */
const app = express()

/**
 * Query whatever DB you have to get a mapping of ID --> Logo URL
 */
const logos = await db.query(`select id, logoUrl from companies`)

/**
 * Convert the logos list to an object for O(1) lookups
 */
const logosKeyedByID = keyBy(logos, 'id')

/**
 * Include one endpoint with a single parameter (the ID) the lookup a logo URL
 */
app.get('/:id', (req, res, next) => {
  const id = get(req, ['query', 'id'])
  
  /**
   * Handle bad request
   */
  if (!id) {
    return next('No ID provided')
  }
  
  /**
   * Lookup the Logo with some default URL
   */
  const logo = get(logosKeyedById, [id, 'logoUrl'], 'some default logo URL')
  
  /**
   * Send back the logo URL
   */
  res.status(200).send(logo)
})

/**
 * Listen
 */
app.listen(process.env.PORT, () => {
  console.log(`Server listening on ${process.env.PORT}`)
})