Teach Me How To JavaScript

Glavin Wiechert

Basics
Browser
Backend

Basics

  • History
  • Language Syntax & Semantics
  • Intro to Callback & Promise style programming

JavaScript History

  • Developed by Brendan Eich working for Netscape Communication Corporation
  • Called LiveScript when shipped in beta Netscape Navigator 2.0 in Sept 1995
  • Renamed JavaScript in Netscape browser v2.0B3
    • marketing ploy by Netscape

Node.js History

  • Created and first published for Linux use in 2009
  • Developed by Ryan Dahl
  • Sponsored by Joyent
  • npm introduced in 2011
    • Create by Isaac Schlueter
  • June 2011 - Microsoft partnered with Joyent to create native Windows version of Node.js
    • released in July
  • Jan 2012 - Isacc Schlueter became project manager
  • Jan 2014 - Timothy J Fontaine is new project lead

Syntax & Semantics

  • Derived from C
  • Case sensitive
  • `var` keyword to declare variables
  • `=` Assignment Operator
  • Literals are fixed values
  • Statements are separated by semicolons
  • Comments
    • // are single-line
    • /* multi-
      line */
  • Single-Threaded
  • Event-driven
  • Prototype-based (OOP)
  • Dynamically typed
  • Functions are first class
    • supports passing functions as arguments and/or returning functions as values

Literals

  • Number literals
    • 3.14
    • 1001
    • 123e5
  • String literals
    • "John Doe"
    • 'John Doe'
  • Expression literals
    • 5+6
    • 5*10

Functions

  • `function` keyword, followed by name, followed by () with code placed between {}
  • parameters are comma separated between ()
  • code within {} can optionally `return`
  • invocation of function is `functionName(param1, param2, etc)`
// This is a single-line comment
// Are you ready for more?
var myName = "Glavin"; // Note that you can also put comments after your code statements
var myAge = 20;
// ^ CamelCase is the common form to write variable names in JavaScript

/*
This is a multi-line comment.
This is very helpful,
especially when you like to talk a lot.
*/
function whoami(name, ageInYears) {
  // Let's do some arithmetic.
  var ageInDays = 365 * ageInYears; // Yes, this math is total BS. Let me have this one :)
  // String concatenation is easy in JS!
  // Notice how ageInDays is a Number and I can simply + it with a String.
  return "My name is "+name+" and I am "+ageInDays+" days old!";
}

/* Invoke a function.
Arguments are myName and myAge.
Inside the function they are mapped arguments to local variables, parameters.
Argument -> Parameter
myName -> name
myAge -> ageInYears
*/
var result = whoami(myName, myAge);
console.log(result);
/* 
`result` variable is equal to
"My name is Glavin and I am 7300 days old!"
*/

Callbacks vs Promises

Callback

Promise

fs.readFile('test.txt', function (err, data) {  
    if (err) return console.error(err);
    db.insert({
        fileName: 'test.txt',
        fileContent: data
    }, function (err, result) {
        if (err) return console.error(err);
        smtp.send({
            to: 'test@test.com',
            subject: 'test',
            body: 'This is a test.'
        }, function (err) {
            if (err) return console.error(err);
            console.log("Success email sent.");
        });
    });
});
fs.readFile('test.txt')  
    .then(function (data) {
        return db.insert({
            fileName: 'test.txt',
            fileContent: data
        });
    })
    .then(function () {
        return smtp.send({
            to: 'test@test.com',
            subject: 'test',
            body: 'This is a test.'
        });
    })
    .then(function () {
        console.log("Success email sent.");
    }, function (err) {
        console.error(err);
    });

Callback & Promise style

Browser

  • Browser APIs
    • Web-Workers (Multithreading)
    • File API
    • Drag'n'Drop
    • WebGL
  • jQuery
    • Manipulating the DOM
    • Making HTTP requests to APIs
  • Popular Front-End Tools
    • Design - Twitter Bootstrap
    • Graphing - D3 (NVD3, C3)
    • MVC Frameworks - Angular, Ember, Backbone, etc

Internet Explorer

To Web-Developers

Lesson 1:

Check Browser Support

Use  http://caniuse.com/

Web-Workers

File API

Drag'n'Drop

WebGL

jQuery

Let's talk about

the DOM, baby

jQuery and the DOM

  • DOM = Document Object Model
  • Without jQuery: document.getElementById(), document.getElementsByClassName(), etc
  • Pass CSS selector to jQuery and easily get access to jQuery elements!


     
  • jQuery elements, unlike DOMElement, have special features that can be used to make web-dev life easier


     
// Get the <button> element with the class 'continue' 
// and change its HTML to 'Next Step...'
$( "button.continue" ).html( "Next Step..." );

// Show the #banner-message element that is hidden with `display:none` 
// in its CSS when any button in `#button-container` is clicked.
var hiddenBox = $( "#banner-message" );
$( "#button-container button" ).on( "click", function( event ) {
  hiddenBox.show();
});

Backend Communication

Popular Front-End Tools

  • Design
    • Twitter Bootstrap
  • Graphing
    • D3 (NVD3, C3)
  • MVC Frameworks
    • Angular, Ember, Backbone, etc

Bootstrap

  • "Bootstrap is the most popular HTML, CSS, and JS framework for developing responsive, mobile first projects on the web."

  • http://getbootstrap.com/

MVC Frameworks

D3

Backend with Node.js

  • Native Libraries
    • path
    • fs (filesystem)
    • events (EventEmitter)
  • Creating your own Node.js module
    • Exposing methods and variables
    • Publishing to npm
  • Popular Third-Party Libraries
    • npm & bower & grunt & yeoman
    • Express
    • Socket.io
  • Node.js servers for the win!
  • C++ + Node.js = <3

Event Loop

Why Node.js is Sexy

Event Loop

Working with Files

  • Unlike Browser JS, Node.js as built-in support for interacting with File-System
// Require `fs` module
var fs = require("fs");
var fileName = "foo.txt";

// Reading from File System 
fs.readFile(fileName, "utf8", function(error, data) {
  console.log(data);
});

// Writing to File System
fs.writeFile("/tmp/test", "Hey there!", function(err) {
    if(err) {
        console.log(err);
    } else {
        console.log("The file was saved!");
    }
}); 

// Watch file change events
fs.watch(fileName, {
  persistent: true
}, function(event, filename) {
  console.log(event + " event occurred on " + filename);
});

It's Coding Time!

https://github.com/SMU-CS-and-Math-Society/TMHTN

Thanks for watching!

  • http://www.sitepoint.com/accessing-the-file-system-in-node-js/
  • http://www.toptal.com/nodejs/why-the-hell-would-i-use-node-js
  • https://github.com/joyent/node/tree/master/test/addons/hello-world
  • http://blog.caustik.com/2012/08/19/node-js-w1m-concurrent-connections/
  • http://www.sitepoint.com/accessing-the-file-system-in-node-js/
  • http://www.slideshare.net/nsm.nikhil/writing-native-bindings-to-nodejs-in-c
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