Introduction to Node.js

JS u browser-u

JS u browser-u

JS izvan browsera

JS izvan browser-a

libuv

Generating a basic web server using Node.js and npm

Web Server

A web server is software designed to respond to requests over the internet by loading or processing data

HTTP - Hypertext transfer protocol

  • Web servers follow Hypertext Transfer Protocol (HTTP)
  • HTTP is a protocol which allows the fetching of resources
    • such as HTML documents
    • foundation of any data exchange on the Web
    • client-server protocol
    • requests are initiated by the recipient, usually the Web browser

GET and POST

  • One way that a client  and server communicate is through HTTP verbs
  • Verbs indicate what type of request is being made
    • the user is trying to load a new web page
    • the user is updating information in their profile page
  • Two most widely used HTTP methods are GET and POST

Request-response cycle

Creating a Node.js module

Node.js modul

  • A Node.js application is made up of many JavaScript files
  • Each JavaScript file or folder containing a code library is called a module 

JavaScript objects and adding properties

export object and require function

Constructing a Node.js application with npm

npm

  • npm - a package manager for Node.js
  • npm is responsible for managing the external packages
    • install
    • remove
    • modify

npm

npm

  • npm install <package>
    • --save
    • --global
  • npm install <package>
    • -S
    • -g
  • npm install <package>
    • --save-dev
    • --save-prod

Installing a Node.js package with npm

package.json

  • Every Node.js application or module contains a package.json file
    • defines the properties of the project
  • positioned at the root level of the project
  • specifies:
    • the version of current release
    • the name of application
    • the main application file

package.json

{
  "name": "recipe_connection",
  "version": "1.0.0",
  "description": "An app to share cooking recipes",
  "main": "main.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Jon Wexler",
  "license": "ISC",
}

Instalacija paketa

npm install cities --save
{
  "name": "recipe_connection",
  "version": "1.0.0",
  "description": "An app to share cooking recipes",
  "main": "main.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Jon Wexler",
  "license": "ISC",
  "dependencies": {
    "cities": "^2.0.0"
  }
}

Instalacija paketa

Processing request and generating response

JavaScript functions

  • Function is a "subprogram" that can be called by code external (or internal in the case of recursion) to the function
  • In JavaScript, functions are first-class objects
    • they can have properties and methods like any object
    • what distinguishes them from other objects is that functions can be called
    • they are Function objects.

JavaScript arrow functions

  • Arrow functions are anonymous functions with their own special syntax that accept a fixed number of arguments, and operate in the context of their enclosing scope - i.e. the function or other code where they are defined.

sitepoint.com

 =>

HTTP Status Codes

Callback function

  • A callback is an anonymous function that’s set up to be invoked as soon as another function completes
    • benefit of using callbacks is that server
      doesn’t have to wait for the original function to complete processing before running other
      code

Callback function

Running a web server in your browser

node main.js