write-stream-callback.js

const fs = require('fs')

const stream = fs.createWriteStream('large-file.txt')
stream.write('text\n', () => {
  console.log('Wrote first chunk')
})
for (let i = 0; i < 10000000; i++) {
  stream.write('text\n')
}
stream.end(() => {
  console.log('Wrote last chunk')
})