Reading-Notes

code fellows 201

Read: 06 - JS Object Literals; The DOM

[JavaScript & JQuery]

Chapter 3: Object Literals (p. 100-105 ONLY)

Objects

Objects are like data base objects. It is like a personel folder that stores various forms of information. Properties are variables stored within an object. Methods, like properties to variables, are what you call functions stored in an object.

// example of object named hotel
var hotel = {
// these are properties
  name: 'Quay',
  rooms: 40 '
  booked: 25,
  gym: true,
  roomTypes: ['twin', 'double', 'suite'],
// this is a method
  checkAvailability: function() {
    return this.rooms - this.booked;
  }
};

The key is how you define the variables and functions. they are on the left side of the ‘:’. The values are what is contained within the key, there are what follows the ‘:’.

Accessing an Object

There are 2 ways to acces an object, dot notations and the square bracket method.

Dot Notation

var hotelName = hotel.name; var roomsFree = hotel.checkAvailability(); The property to the right of the . is within the object stated on the right. The variable on the left is declared to hold the information of the object called.

Square Bracket

var hotelName = hotel['name']; var roomsFree = hotel['checkAvailability'](); You use this notation when:

• name of property contains special characters like a dash
• name of property is a number
• a variable is used in place of property name

Chapter 5: Document Object Model (p. 183-242)

The Document Objective Model (DOM) is a visual representation of how browsers create HTML pages and how JavaScript acesses and updates contents in the page.

Nodes

When you load an html file the browser creates a mode that is stored in the browser’s memory. This is a DOM tree. It has four main nodes:

Document Node

The Document Node is the starting point of the tree. It sits at the top. It represents the entire page as a whole.

Element Node

The Element Node