index.js

const express = require('express')
const logger = require('morgan')

const google = require('googleapis')
const books = google.books('v1')

// Initializing the App
const app = express()
app.use(logger('dev'))

// Enable CORS from client-side
app.use(function (req, res, next) {
  res.header('Access-Control-Allow-Origin', '*')
  res.header('Access-Control-Allow-Methods', 'PUT, GET, POST, DELETE, OPTIONS')
  res.header('Access-Control-Allow-Headers', 'Origin, X-Requested-With, Content-Type, Accept, Authorization, Access-Control-Allow-Credentials')
  res.header('Access-Control-Allow-Credentials', 'true')
  next()
})

// Routes
app.get('/', (req, res) => {
  res.json({'state': 'Welcome to Google Search server'})
})

app.get('/search/:title', (req, res) => {
  let bookTitle = req.params.title
  let startIndex = req.query.start
  let maxResults = req.query.max
  console.log(startIndex)
  books.volumes.list({
    q: bookTitle,
    startIndex,
    maxResults
  }, (err, result) => {
    if (err) {
      res.json(err)
    } else {
      res.json(result)
    }
  })
})

app.get('/books/:bookId', (req, res) => {
  let bookId = req.params.bookId
  books.volumes.get({volumeId: bookId}, function (err, result) {
    if (err) {
      res.json(err)
    } else {
      res.json(result)
    }
  })
})

// Starting the server
app.listen(3030, () => {
  console.log('Server is running at http://127.0.0.1:3030')
})