Web based

1. WEB TECHNOLOGY
TEAM NAME:WEB HOST
TEAM MEMBERS:BHAVANA G
BINDHUSHREE R
NEELIMA REDDY
LIKITHASHREE

2. JAVASCRIPT OBJECTS AND CONSTRUCTORS
OBJECTS IN JAVASCRIPT
Objects, in JavaScript, is the most important data-type and forms the
building blocks for modern JavaScript. These objects are quite different from
JavaScript’s primitive data types (Number, String, Boolean, null, undefined
and symbol) in the sense that while these primitive data-types all store a
single value each (depending on their types).
Syntax:
let object_name = {
key_name : value,
...
}

3. Let us look at an example of a JavaScript Object
below :
<script>
// JavaScript code demonstrating a simple object
let school = {
name: 'Vivekananda School',
location : 'Delhi',
established : '1971',
displayInfo : function(){
console.log(`${school.name} was established
in ${school.established} at ${school.location}`);
}
}
school.displayInfo();
</script>
OUTPUT:Vivekananda School was established.

4. In this example “name”, “location”, “established” are
all “keys” and “Vivekananda School”, “Delhi” and
1971 are values of these keys respectively. Each of these
keys is referred to as properties of the object. An object in
JavaScript may also have a function as a member, in which
case it will be known as a method of that object.
Here “displayinfo” is a method of the school object that is
being used to work with the object’s data, stored in its
properties.

5. • Objects are more complex and each object may contain any
combination of these primitive data-types as well as reference
data-types.
• An object is a reference data type. Variables that are assigned a
reference value are given a reference or a pointer to that value.
That reference or pointer points to the location in memory
where the object is stored. The variables don’t actually store the
value.
• Loosely speaking, objects in JavaScript may be defined as
an unordered collection of related data, of primitive or
reference types, in the form of “key: value” pairs. These
keys can be variables or functions and are called properties and
methods, respectively, in the context of an objec

6. Properties of JavaScript Object
• The property names can be strings or numbers. In case the property names are numbers,
they must be accessed using the “bracket notation” like this :
<script>
let school = {
name: 'Vivekananda School',
location : 'Delhi',
established : '1971',
20 : 1000,
displayInfo : function(){
console.log(`The value of the key 20 is ${school['20']}`);
}
}
school.displayInfo();
</script>
OUTPUT:The value of the key 20 is 1000.

7. •But more on the bracket notation later. Property names
can also be strings with more than one space separated
words. In which case, these property names must be
enclosed in quotes :
let school = {
"school name" : "Vivekananda School",
}

8. CREATING OBJECTS
• There are several ways or syntax’s to create objects. One of which, known as
the Object literal syntax, we have already used. Besides the object literal syntax,
objects in JavaScript may also be created using the constructors, Object
Constructor, or the prototype pattern.
• Using the Object literal syntax : Object literal syntax uses the {…} notation to
initialize an object an its methods/properties directly. Let us look at an example
of creating objects using this method :
• var obj = {
• member1 : value1,
• member2 : value2,
• };

9. OBJECTS INCLUDED IN JAVASCRIPT
A Number of useful objects are included with JavaScript including:
Array
Boolean
Date
Math
String
Dom objects

10. Arrays
Arrays are one of the most used data structures.in practise,this class is
defined to behave more like a linked list in that it can be resized
The following code creates a new,empty array named
greetings:
Var greetings=new Array();
To initialize the array with values,the variable declaration would look like
the following:
Var greetings=new Array(“Good Morning”,”Good Afternoon”);

11. DOCUMENT OBJECT
• The DOM document object is the root JavaScript object representing
the entire HTML document.
• It contains some properties and methods that we will use extensively
in our development and is globally accessible as document.
//specify the doctype,for example html
var a=document.doctype.name;
//specify the page encoding,for example ISO-8859-1
var b=document.inputEncoding;

12. JAVASCRIPT BOOLEANS
• A JavaScript Boolean represents one of two values:
true or false.
THE BOOLEAN()FUNCTION
You can use the Boolean() function to find out if an expression(or a
variable)is true:
EXAMPLE:
Boolean(10 > 9)

13. JAVASCRIPT DATA OBJECT
• The JavaScript date object can be used to get year,month and day .you can
display a timer on the webpage by the help of JavaScript date object.
• SYNTAX
You can use any of the following syntaxes to create a Date objects using Date()
constructor.
new Date()
new Date(milliseconds)
new Date(datestring)
NOTE:Parameters in the brackets are always optional.

14. JAVASCRIPT MATH OBJECT
• The JavaScript Math object allows you to perform mathematical tasks
on numbers.
• EXAMPLE
Math.E // returns Euler’s
number

15. CONSTRUCTORS
• Normally to create a new object we use the new keyword, the class
name, and()brackets with n optional parameters inside, comma
delimited as follows:
var someObject = new ObjectName(p1,p2,….., pn)
; for some classes, shortcut constructors are
defined var greeting=“Good Morning”;
Vs the formal:
Var greeting = new String(“Good Morning”);

16. <script>
function Vehicle(name, maker) {
this.name = name;
this.maker = maker;
}
let car1 = new Vehicle('Fiesta', 'Ford');
let car2 = new Vehicle('Santa Fe', 'Hyundai’)
console.log(car1.name); // Output:
Fiesta
console.log(car2.name); // Output:
Santa Fe
</script>

17. THANK YOU