Mcsd 70-480 1.5-1.6 Objects, Variables, Methods & Scope

Front 1

"this" keyword

Back 1

Refers to the object that owns the code that is currently running. In an event handler it refers to the object that triggered the event.

Front 2

register an event handler

Back 2

myElement.onClick = myEventHandler where myEventHandler() is a function

Front 3

global variables

Back 3

variables available to all other areas of the program from the moment they are defined until the page is closed.

Front 4

local variables

Back 4

variables scoped to be available only in the code block where they are declare until the execution leaves the code block.

Front 5

Basic IIFE syntax

Back 5

(function() {// hidden code and objects go here })();

Front 6

IIFE (immediate invoked function expression)

Back 6

keeps objects out of global namespace by declaring an anonymous function and then immediately exectuing it.

Front 7

Basic Revealing Module Pattern Syntax

Back 7

var myModule = (function() { var x = 1; var y = 2; var myFunction = function() { return x + y; };return { getX: function() { return x; }, // public getter for X setX: function( newX) { x = newX; }, // public setter for X myFunction : myFunction // make myFunction public } })();

Front 8

Revealing Module Pattern

Back 8

Keeps objects out of global namespace by using IIFE but returning an object that has accessible properties and methods.

Front 9

Common javascript native objects

Back 9

Array, Date, Math, RegExp, String

Front 10

Math Object

Back 10

A static native javascript object for performing mathmatical functions like Math.PI or Math.sqrt(16);

Front 11

Create new instance of native object

Back 11

var myArray = new Array();

Front 12

Call toUpperCase() String object method

Back 12

var myString = new String("hello"); myString.toUpperCase(); or "hello".toUpperCase();

Front 13

Create a custom object

Back 13

var Cat = function(size, color) { this.size = size; this.color = color; } and var myCat = new Cat("fat", "white");

Front 14

Prototypes

Back 14

represent the definition of the object type, like a blueprint, and changing the prototype changes all of the objects that were built from it.

Front 15

Prototype function

Back 15

Cat.prototype.meow = function(volume) { this.volume = volume; }

Front 16

Prototype property

Back 16

Cat.prototype.name = 'Whiskers';

Front 17

Custom Methods for native objects syntax

Back 17

String.prototype.GetFirstChar = function() { return this.charAt(0); } and myString.GetFirstChar();

Front 18

Inherit From an Object

Back 18

function RaceCar( topspeed) { Car.call( this); // call our base class constructor to inherit from that class this.topspeed = topspeed; // extend with our new properties }