Intro to Node.js

Intro to Node.js

What is Node.js

Writing Node

The fs Module

What is Node.js for?

Full Stack Engineering

Components of The “Stack”

THE CLIENT SIDE

Consuming APIs,

Client Routing

THE INTERNET

HTTP protocol

IP protocol

DNS

CDNs

Networking

THE SERVER SIDE

Request Routing,

Asset Delivery,

Creating APIs,

Databases,
Data Processing

Remember This?

Full Stack Engineering

Components of The “Stack”

THE CLIENT SIDE

Consuming APIs,

Client Routing

THE INTERNET

HTTP protocol

IP protocol

DNS

CDNs

Networking

THE SERVER SIDE

Request Routing,

Asset Delivery,

Creating APIs,

Databases,
Data Processing

Node.js - The Server Side

THE SERVER SIDE

Request Routing,

Asset Delivery,

Creating APIs,

Databases,
Data Processing

Node is really just

A program

Node is really just

A program

That runs on your computer

Node is really just

A program

That runs on your computer

That executes JavaScript

Node is really just

A program

That runs on your computer

That executes JavaScript

ECMAScript 2015... ish

Not your grandmother's JavaScript

ECMAScript 2015... ish

No access to Browser APIs

document

window

New Features!

ECMAScript6 Node.js Support

Module System!

Node Package Manager (NPM)

Node.js - Components

Node.js - Components

$ node

- A program on your computer that runs JavaScript

Node.js - Components

$ node

- A program on your computer that runs JavaScript

$ npm

- Node Package Manager, like `brew` for node!

$ node

var greeting = "Hello, ";

console.log(greeting + "class!");

To start:

$ node greeting.js
Hello, class!

greeting.js:

$ node

What's the point of all this?

$ node

$ node

APIs

Filesystem

HTTP / HTTPS

OS

C / C++ Wrappers (for Internet of Things!)

Network

Many Others!

$ node

is event-driven

$ node

is event-driven

Asynchronous I/O

Single-Threaded

$ node

Using

moduleName.asyncMethod("param1", function(err, data) {
    //err will be empty if there was no error
    if (!err) {
        doSomethingWith(data);
    } else {
        console.log("there was an error!" + err);
    }
});

A typical node.js pattern - Async I/O

These do something asynchronous, and then execute a callback

$ node

Using

var eventEmitter = moduleName.createEventEmitter("thing");

eventEmitter.on("someEvent", function(err, data){
    console.log(err);

    console.log(data);
});

eventEmitter.on("someOtherEvent", function(err, result) {
    if (err) throw err;

    console.log(result);
});

A typical node.js pattern - Evented I/O

These events can happen in any order!

$ node

Using

Using Modules

var myModule = require("aModule");

module.doSomething()

var thing = module.createSomething();

thing.on("event", function(){
    // do something
});

thing.doSomethingAsync(params, function(){
    // do something when done
});

$ node

APIs

var os = require("os");

os.hostname();

os.networkInterfaces();

os.uptime();

OS - just read access

$ node

APIs

Filesystem - Async pattern

var fs = require("fs");

fs.readFile("./log.txt", function(err, data){
    var myFile = data.toString();
    console.log(myFile)
});

$ node

APIs

var http = require("http");

var server = http.createServer();

server.on("request", function(request, response) {

	response.end("Hello");

});

server.listen(9021, function(err){
    if (err) {
        console.log(err);
    } else {
        console.log("I've connected!");
    }
});

HTTP / HTTPS - Evented