index.js

// Requirements:
// A student management app that is able to:
// - Show current student list
// - Add new students
var readlineSync = require('readline-sync');
var fs = require('fs');

var students = [];

function loadData() {
  var fileContent = fs.readFileSync('./data.json');
  students = JSON.parse(fileContent);
}

function showMenu() {
  console.log('1. Show all students');
  console.log('2. Create a new student');
  console.log('3. Save & Exit');

  var option = readlineSync.question('> ');
  switch (option) {
    case '1':
      showStudents();
      showMenu();
      break;
    case '2':
      showCreateStudent();
      showMenu();
      break;
    case '3':
      saveAndExit();
      break;
    default:
      console.log('Wrong option');
      showMenu();
      break;
  }
}

function showStudents() {
  for (var student of students) {
    console.log(student.name, student.age);
  }
}

function showCreateStudent() {
  var name = readlineSync.question('Name: ');
  var age = readlineSync.question('Age: ');
  var student = {
    name: name,
    age: parseInt(age)
  };
  students.push(student);
}

function saveAndExit() {
  var content = JSON.stringify(students);
  fs.writeFileSync('./data.json', content, { encoding: 'utf8' });
}

function main() {
  loadData();
  showMenu();
}

main();