slide môn học HDJ bài 8 the core language objects in javascript

 Work on Core Language Objects  Use object Attributes and Methods...  The properties variables that define the object and the methods functions that work on the data are included in t

The Core language Objects in JavaScript

Session 8

A Recap

 Scripting Language – Scenarios Language

 JavaScript’s Elements

 Core JavaScript Object

 Client-Side JavaScript Object

 Server-Side JavaScript Object

 Work on Core Language Objects

 Use object Attributes and Methods

 The properties (variables) that define the object and the methods (functions) that work

on the data are included in the object

 For example, a car is an object The properties of the car are its make, model, and color They have some common methods like,

go (), brake(), reverse()

Properties and Methods

 To access the properties of the object, we must specify the object name and the property:

objectName.propertyName

 To access the methods of an object, we must

specify the object name and the required method:

objectName.method ()

Using objects

 When creating a Web page we can insert:

 Browser objects

 Built in script language objects (vary depending

on the scripting language used)

 HTML elements

 We can also create our own objects for use

in the programs

Object Hierarchy

Browser Objects

Script Objects

HTML Elements

The this statement

 The this statement is more of an internal property

 Its value indicates the current object It can have standard properties such as name, length and value applied accordingly

The for in statement

 The for in statement is used to cycle through each property of an object or each element of an array

 The syntax is:

for (variable in object)

{ statements; }

The with statement

 The with statement is used to execute a set

of statements that have a specified object as the reference

 The property is assigned to the object specified in the with statement

 The syntax is:

with (object) { statements; }

New Operator

 The new operator is used to create a new

instance of an object type

 The object type may be user-define or built-in

 objectName = new objectType (param1

[,param2] [,paramN])

where,

objectName is the name of the new object instance.

ObjectType is a function that defined the type of the object For

example, Array.

Eval function

 The eval function is used to evaluate a string

of code without reference to any specific

object

 The string can be a JavaScript expression,

statement, or a group of statements

 The expression can include variables and

properties of an object

var x = 5;

var z = 10;

document.write(eval(“x + z + 5”));

Creating String object

 There are 3 different methods of creating

Math Object

 The Math object has properties and

methods that represent advanced

}

Date object

 The Date object stores dates as the number

of milliseconds since January 1, 1970,

00:00:00

DateObject = new Date(parameters)

 One Shot Timer

 setTimeout(“javaScript code”, delay)

 Timer that Fires at Regular Intervals

 setInterval(“javaScript code”, interval)

 clearInterval(handler)