Dangers of mixing blocking and non-blocking code

mixing-and-non-blocking-code.js

// Mix
const fs = require('fs')
fs.readFile('/file.txt', (err, data) => {
  if (err) throw err
  console.log(data)
})
fs.unlinkSync('/file.txt')

// Better way
const fs = require('fs')
fs.readFile('/file.txt', (readFileErr, data) => {
  if (readFileErr) throw readFileErr
  console.log(data)
  fs.unlink('/file.txt', (unlinkErr) => {
    if (unlinkErr) throw unlinkErr
  })
})