Variables, constants, and arrays are used to store data in JavaScript. Variables store single values that can change during a program, constants store single fixed values, and arrays store multiple values of the same type in indexed elements. Common data types stored include numbers, strings, Booleans, objects, and more. Proper naming conventions use camelCase for variables and arrays and ALL_CAPS for constants.

1. Storage
Variables
Constants
Arrays

2. Kinds of Data
• User generated data
• Program Data
User Inputs
Storage
var msg="Hello World"
Program Data

3. User Generated Data
Input
User Generated Data
Interact
User Interaction
Program
Content

4. Program Data
Data available beforehand
Data processed via program

5. janData
janData
Variable
Variable and Constant
PI
PI
Constant
Storage
Storage

6. Variable
• Named storage location in memory
• By convention follow 'Camel Case' for naming
Eg:
– bigApple
– usbMic
• Value may change during program processing
• Can hold a single value

7. Variable
• Use word-let
let message = "Hello World";
alert (message);
let bigApple = 20;
alert(bigApple);
let user='Gauri', age= 20, message='Good Day';
alert(message + " "+user +" "+ age);

8. Constant
• Named storage location in memory
• By convention follow 'All Caps' for naming. Eg:
– BIGAPPLE
– USBMIC
• Value may never change during program
processing
• Can hold a single value

9. Constant
• Use word- const
const piv = 3.14;
window.alert("Value of pi: "+ piv);

10. Data Type
• Data is any form of information
• Number
– Integer
– Decimal
• String
– Combination of characters, integers and symbols
• Boolean
– Yes/No

11. Data Type
• Null
– Null value
• Undefined
– Variable or Constant that is not initialized
• Object
– Complex data structures
• Symbol
– Unique Identifiers

12. Array
• Named storage location in memory
• Can hold multiple values of same data type
• By convention follow 'Camel Case' for a variable array
name or 'All Caps' for a constant array name. Eg:
– bigApple
– usbMic
• Name should be plural since array is collection of
values.
• Value of variable array may change during program
processing
• Value of constant array may change during program
processing but cannot be reassigned

13. Array
23 45 33 65 76 77
7 4 3 6
apple[0] apple[1] apple[2] apple[3] apple[4] apple[5]
INTR[0] INTR[1] INTR[2] INTR[3]
An array index always starts from 0. If we have an array of 10
elements, then the elements to be referred to will be 0-9. Here,
the length of array will be 10.
For example: Integer array of 6 elements for storing the price of 6 varieties of
apple.
var apple = new Array(6);
apple[0] = 23;……
Integer array of 4 elements for storing the interest rate of 4 bank products
eg. Fixed Deposit, Saving A/c, Current A/c, Recurring Deposit will be constant.
const INTR = new Array(4);

14. JAN
FEB
MAR
APR
MAY
JUN
JAN
FEB
MAR
APR
MAY
JUN
Array
Array

15. Difference
Variables Constants Arrays
Value may vary. Value can
change once or multiple
times via processing
during the lifetime of
program.
Value remains constant.
Cannot change through
out the lifetime of
program.
Value may vary for each
element individually
during the lifetime of
program.
Stores single value Stores single value Stores multiple values
depending on the length
of array in different
elements.

16. Storing data in JS
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