# Node.js Introduction

* Node.js is an open source server environment
* Node.js is free
* Node.js runs on various platforms (Windows, Linux, Unix, Mac OS X, etc.)
* Node.js uses JavaScript on the server

## Run the first app on node.js

console.log("hello world!");

const fs = require('fs');
fs.writeFileSync('hello.txt', 'hello world!');

## Javascript on server

## Node.js role for web development

## Outline
* Javascript refresher
* Using expressjs framework for web development
* MVC
* Routes & models
* With db (Mysql) or (MongoDB)
* Authentication
* Error handling
* REST API
* GraphQl
* Deployment

### Javascript refresher

const name = 'Max';
let age = 29;
const hasHobbies = true;

age = 30;

const summarizeUser = (userName, userAge, userHasHobby) => {
  return (
    'Name is ' +
    userName +
    ', age is ' +
    userAge +
    ' and the user has hobbies: ' +
    userHasHobby
  );
};

const addRandom = () => 1 + 2;
console.log(addRandom());

console.log(summarizeUser(name, age, hasHobbies));

### nodejs Module
How to create nodejs module and how to use it

exports.myDateTime = function () {
  return Date();
};