but i have a

Microsoft

background

Thank-you

for sponsoring this great venue

Thank-you

BBD, Entelect and Amazon Development Center

Back to our regularscheduled programming...

JavaScript

Looked like C and Java

Ran in a browser

And on the server

Wasn't VB

Not here to talk about me

What are classes?

Or at least, what do we care about?

When I lie to you, I'll mark it with a †

We care about Classes that...

• define reusable properties and methods
• can inherit functionality from a superclass
• can override functionality of their superclass
• can call their superclass methods
• are open (can be Monkey-patched)

(that last one, from a Rubyist perspective)

JavaScript

But it is possible to treat JavaScript "classes" very much like classical classes while also taking advantage of some of the dynamic nature of JS.

Object Properties

Key → Value

• Keys are strings
• Values can be anything:
  • A number or a string or other type
  • Another object or array (which is an object)
  • Or a function (method)

Inherited Object Properties

• All objects inherit from Object†
• #toString
• #valueOf
• And a whole whack of other methods

Inheritance

• __proto__†
• [[prototype]]
• Functions are constructors
• new Object() is calling a function
• with this special bit of syntactic sugar new

new Keyword

• creates an {}
• {}.__proto__ = Constructor.[[prototype]]
• Constructor.call({}, arguments)
• return {}†

Classes

Constructor.prototype.method =   function() { ... }

Can also override methods

Privacy

• Nothing is private
  • _method
  • __method
  • __method__

IIFE

• Immediately-Invoked Function Expression
  • Pronounced Iffy
  • Often incorrectly named SIF
• (function(global, undefined) {})(this)
  • Everything is private
  • Unless you make it public

More uses for IIFEs

• Pass more interesting things in
  • Mixing up multiple libraries?
  • (function($) {})(jQuery)

Gotcha

In strict mode, this is not coerced to the global object

Functions

• First class
• apply
• call
• bind

First Class Functions

• Pass functions as arguments
• Return functions from functions
• Assign them to variables or in data structures
• Have anonymous functions

Closures

A closure is a function that refers to an independant variable.

Eisbein IFFE total and cook referred to count.

Binding

• bind
• $el.on('click', this.onClick.bind(this))

Other options

• CoffeeScript
• TypeScript
• ES6