reading-notes

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HTML Tables; JS Constructor Functions

Domain modeling

Example of creating a constructor function.

var epicFailVideos = function(epicRating, hasAnimals) {
  this.epicRating = epicRating;
  this.hasAnimals = hasAnimals;
}

var parkourFail = new epicFailVideos(7, false);
var corgiFall = new epicFailVideos(4, true)

object oriented programing

• The new keyword instantiates (i.e. creates) an object.
• The constructor function initializes properties inside that object using the this variable.
• The object is stored in a variable for later use.

Key notes

• When modeling a single entity that’ll have many instances, build self-contained objects with the same attributes and behaviors.
• Model its attributes with a constructor function that defines and initializes properties.
• Model its behaviors with small methods that focus on doing one job well.
• Create instances using the new keyword followed by a call to a constructor function.
• Store the newly created object in a variable so you can access its properties and methods from outside.
• Use the this variable within methods so you can access the object’s properties and methods from inside.

Chapter 6: “Tables” (pp.126-145)

use <tabel> element in HTML.

• th = table header
• tr = table row
• td = table data

Chapter 3: “Functions, Methods, and Objects” (pp.106-144)

The new keyword and the object constructor create a blank object. You can then add properties and methods to the object.

var hotel = new Object();

hotel.name= 'quay';
hotel.rooms = 40;
hotel.booked = 25;

hotel.checkAvailability = function() {
  return this.rooms - this.booked;
};

To update values of properties, use dot notation or square brackets. They work on objects created. To delete properties use delete keyword;

hotel.name = 'park'; //changes property
delete hotel.name; // deletes property

you can use functions to create objects.

function hotel(name,rooms, booked){
  this.name = name; // properties
  this.rooms = rooms;
  this.booked = booked;

  this.checkAvailability = function() { //method
    return this.rooms - this.booked;
  };
}

You can use the new keyword to followed by a function to created a new object

var quayHotel = new hotel("quay', 40, 25);

Type	Description	Example
Browser Object Model	Contains objects that represent the current browser window or tab. Like browser history
Document Object Model	Uses objects to create a representation of the current page. It creates a new object for each link.
Global Javascript Objects	represent things that the java script language needs to create a model of.

The Window object

Document object

Tell you about the current page

Property	Description	Example
document.title	Title of current document
document.lastModified	Date on which document was last modified
document.URL	Returns string containing URL of current document
document.domain	returns domain of current document

Amending contents of the page Method | Description| Example —- | —- | —- document.write() | writes text to document document.getElementById() | Returns element, f there is an element with the value of the id attribute that matches document.querySelectionAll() | Returns list of elements that match a CSS selector, which is specified as a parameter document.createElement() | Creates new element (p222) document.createTextNode() | Creates new text node (p222)

Global Objects

Property	Description	Example
length	returns number of character in the string in most cases

Method	Description	Example
toUpperCase()	Changes string to uppercase characters
toLowerCase()	Changes string to lower case characters
charAt()	Takes an index number as a parameter and returns the character found at that position
indexOf()	Returns index number of the first time a character or set of characters ifs found within the string
lastIndexOf()	Returns index number of the last time a character or set of characters is found within a string.
substring()	Returns character found between two index numbers where the character for the first index number is included and the character for the last index number is not included.
split()	When a character is specified, it splits the string each time it is found, then stores each individual part in an array.
trim()	removes whitespace from start and end of string
replace()	Like find and replace, it takes one value that should be found, and another to replace it. (only replaces the first match it finds)

Number Objects

Method	Description	Example
isNAaN()	Checks if the value is not a number
toFixed()	Rounds to specified number of decimal places
toPrecision()	Rounds to total number of places
toExponential()	Returns a string representing the number in exponential notation.

Math Objects

Property	Description	Example
Math.PI	Returns pi (3.14)

Method	Description	Example
Math.round()	Rounds number to the narest integer
Math.sqrt(n)	Returns square root of positive nubmer
Math.ceil()	Rounds number uup to the nearest integer
Math.floor()	Rounds number down to the nearest integer
Math.random()	Generates a random number between 0

Date Objects

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