learnyounode/exercises/my_first_async_io/solution_vi/solution.js

Learn You The Node.js For Much Win! An intro to Node.js via a set of self-guided workshops.

const fs = require('fs')
const file = process.argv[2]

fs.readFile(file, function (err, contents) {
  if (err) {
    return console.log(err)
  }
  // có thể sử dụng fs.readFile(file, 'utf8', callback) cũng được
  const lines = contents.toString().split('\n').length - 1
  console.log(lines)
})