Introduction to JavaScript Scripting Language

JavaScript Basics
Let’s Start

1. JavaScript is the programming language of the Web.
2. JavaScript is easy to learn
3. JavaScript is the world’s most popular programming Language
Overview

Alert Box in JavaScript
An alert box is used if you want to make sure information comes though to the user.
When an alert box pops up, the user will have to click “OK” .
Syntax:
window.alert(“Text”)

A confirm box is used if we want the user to verify or accept something
When a confirm box pops up, the user will click on “OK” or “Cancel”.
It works on true or false depends on “OK” and “Cancel”.
Syntax:
window.confirm(“Text”)
confirm Box in JavaScript

A Prompt box is used if we want the user to input a value before entering a page.
When a prompt box pops up, the user will have to click on “OK” or “Cancel” to proceed after
entering an input value.
“OK” returns the input value.
“Cancel” returns null
Syntax:
window.prompt(“Text”)
Prompt Box in JavaScript

In JavaScript expression is a valid set of literals , variables , operators that evaluate to a single
value that is an expression.
var x;
let y;
x=8;
y=9;
Let z=x+y;
Fixed values are called as Literals.
Expression in JavaScript

• Arithmetic Operators
• Comparison (Relational) Operators
• Bitwise Operators
• Logical Operators
• Assignment Operators
• Special Operators
Operators in JavaScript

Operator Description Example
+ Addition 10+20 = 30
- Subtraction 20-10 = 10
* Multiplication 10*20 = 200
/ Division 20/10 = 2
% Modulus (Remainder) 20%10 = 0
++ Increment var a=10; a++; Now a = 11
-- Decrement var a=10; a--; Now a = 9
Arithmetic Operators

Comparison Operators
== Is equal to 10==20 = false
=== Identical (equal and of same
type)
10==20 = false
!= Not equal to 10!=20 = true
!== Not Identical 20!==20 = false
> Greater than 20>10 = true
>= Greater than or equal to 20>=10 = true
< Less than 20<10 = false
<= Less than or equal to 20<=10 = false

Bitwise Operators
& Bitwise AND (10==20 & 20==33) = false
| Bitwise OR (10==20 | 20==33) = false
^ Bitwise XOR (10==20 ^ 20==33) = false
~ Bitwise NOT (~10) = -10
<< Bitwise Left Shift (10<<2) = 40
>> Bitwise Right Shift (10>>2) = 2
>>> Bitwise Right Shift with Zero (10>>>2) = 2

Logical Operators
&& Logical AND (10==20 && 20==33) = false
|| Logical OR (10==20 || 20==33) = false
! Logical Not !(10==20) = true

Assignment Operators
= Assign 10+10 = 20
+= Add and assign var a=10; a+=20; Now a =
30
-= Subtract and assign var a=20; a-=10; Now a = 10
*= Multiply and assign var a=10; a*=20; Now a =
200
/= Divide and assign var a=10; a/=2; Now a = 5
%= Modulus and assign var a=10; a%=2; Now a = 0

Special Operators
Operator Description
(?:) Conditional Operator returns value based on
the condition. It is like if-else.
, Comma Operator allows multiple expressions
to be evaluated as single statement.
delete Delete Operator deletes a property from the
object.
in In Operator checks if object has the given
property
instanceof checks if the object is an instance of given
type
new creates an instance (object)
typeof checks the type of object.
void it discards the expression's return value.
yield checks what is returned in a generator by the

Printing basic outputs
In JavaScript we can display data in following ways:
• Writing into an HTML element, using innerHTML.
• Writing into the HTML output using document.write().
• Writing into an alert box, using window.alert().
• Writing into the browser console, using console.log().

Adavntages of JavaScripts
• Speed
• Simplicity
• Popularity
• Interoperability
• Server Load
• Rich Interfaces
• Extended Functionality
• Versatility
• Less Overhead

Introduction to JavaScript Scripting Language

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