server.js

const express = require('express')
const bodyParser = require('body-parser')
const books = require('./db')

const app = express()
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: true }))

app.get('/books', (req, res) => {
  res.json(books)
})

app.get('/books/:id', (req, res) => {
  res.json(books.find(book => book.id === req.params.id))
})

app.post('/books', (req, res) => {
  books.push(req.body)
  res.status(201).json(req.body)
})

app.put('/books/:id', (req, res) => {
  const updateIndex = books.findIndex(book => book.id === req.params.id)
  res.json(Object.assign(books[updateIndex], req.body))
})

app.delete('/books/:id', (req, res) => {
  const deleteIndex = books.findIndex(book => book.id === req.params.id)
  books.splice(deleteIndex, 1)
  res.status(204).send()
})

app.listen(3000, () => {
  console.log('Start server at port 3000.')
})