Sample code for a PCS exercise

addressbook.js

var fs = require('fs');
var read = require('read');

var myBook = [];

var data = fs.readFileSync(__dirname + '/data.json', { encoding: 'utf8', flag: 'a+' });
if (data) {
  myBook = JSON.parse(data);
}

mainPrompt();

var commands = {
  "exit": exit,
  "list": list,
  "help": help,
  "add": addContact
}

function mainPrompt () {
  read({ prompt: '> '}, function (err, result) {
    if (commands.hasOwnProperty(result)) {
      commands[result]();
    } else {
      console.log("Invalid Command");
      mainPrompt();
    }
  });
}


// commands

function help () {
  console.log("You can type: add, list or exit.");

  mainPrompt();
}

function addContact () {
  var name, address, phone = "";

  read({ prompt: 'Enter name >' }, getName);

  function getName (err, result) {
    name = result;

    read({ prompt: 'Enter address >' }, getAddress);
  }

  function getAddress (err, result) {
    address = result;

    read({ prompt: 'Enter phone >' }, getPhone);
  }

  function getPhone (err, result) {
    phone = result;
    
    addToBook();
  }

  function addToBook () {
    myBook.push({name: name, address: address, phone: phone});

    mainPrompt();
  }
}

function exit () {
  saveMyData();
  console.log("See yah!");
  process.exit();
}

function list () {
  myBook.forEach(function (item) {
    console.log(item);
  });

  mainPrompt();
}

// File I/O

function saveMyData () {
  fs.writeFileSync(__dirname + '/data.json', JSON.stringify(myBook, null, '\t'));
}