javascript
	-high level language (now)
        -it can be used as client side and server side
	-not type safe, loosly typed language
        -no main()
        -case sensitive 
        -initially is function oriented but now it support oops
        -extension is .js
        -interpreter based
        -every web browser uses javascript execution engine as a part of them
datatypes 
	-there are no explicit datatypes 
	-to declare a variable, data type is not required.
        -console object is used for output
primitive / abstract
value type / reference 
predefined / user defined

	-implicit datatypes
        -alone variable must be initialized to use it.
        -every variable must declard or initialized to use it.
        - type of variable is decided based on the value assigned to it.
        - any variables value and type can changed

number - when a variable is assigned with numerical value of any kind(floating point & non-floating)
string - when a variable is assigned with a value enclosed by single quotes or double quotes
boolean - when a variable is assigned with true or false
object -  when a variable is assigned with null or [] or {}
undefined - when a variable is assigned with undefined
function - when a variable is assigned with function
bigint   - when a variable is assigned with BigInt()

Price
console.log(Price);
ReferenceError: Price is not defined
----------------------------------------
Price=123.99;
console.log(Price + '   ' + typeof(Price));
----------------------------------------
Price=123.99;
console.log(Price + '   ' + typeof(Price));
Price = 'ashok it';
console.log(Price + '   ' + typeof(Price));
Price = "JavaScript";
console.log(Price + '   ' + typeof(Price));
Price = true;
console.log(Price + '   ' + typeof(Price));
Price = false;
console.log(Price + '   ' + typeof(Price));
-----------------------------------------
Price = null;
console.log(Price + '   ' + typeof(Price));
Price = [];
console.log(Price + '   ' + typeof(Price));
Price = {};
console.log(Price + '   ' + typeof(Price));
---------------------------------------------
function Add(x, y)
{
    console.log(x+y);
}
Add(99,29);
Price =  Add;
console.log(Price + '   ' + typeof(Price));
Price(9,39);
------------------------------------------------
Price= Number();
console.log(Price + '   ' + typeof(Price));
------------------------------------------
Price= Number(199);
console.log(Price + '   ' + typeof(Price));
-------------------------------------------
Price= Number('test');
console.log(Price + '   ' + typeof(Price));
--------------------------------------------
Price= String();
console.log(Price + '   ' + typeof(Price));
---------------------------------------------
Price= String('ashok it');
console.log(Price + '   ' + typeof(Price));
--------------------------------------------
Price= Boolean();
console.log(Price + '   ' + typeof(Price));
-------------------------------------------
Price= Boolean(true);
console.log(Price + '   ' + typeof(Price));
-------------------------------------------
Price= Object();
console.log(Price + '   ' + typeof(Price));
---------------------------------------------
Price= Object(299);
console.log(Price + '   ' + typeof(Price));
-------------------------------------------
Price= Object('ashok it');
console.log(Price + '   ' + typeof(Price));
-------------------------------------------
Price= Object(true);
console.log(Price + '   ' + typeof(Price));
------------------------------------------
Price= Object(null);
console.log(Price + '   ' + typeof(Price));
--------------------------------------------
Price= Date();
console.log(Price + '   ' + typeof(Price));
-------------------------------------------
declare variable
	var 
        let

var Price = 99;
console.log(Price + '  ' + typeof(Price));
------------------------------------------
var Price;
console.log(Price + '  ' + typeof(Price));
------------------------------------------
let Price;
console.log(Price + '  ' + typeof(Price));
-----------------------------------------
let Price=99;
console.log(Price + '  ' + typeof(Price));
-----------------------------------------

Operators 
	Arithmetic +  -  *  /  % **
var x = 10;
var y = 2;
var z = 3;
console.log(x+y);
console.log(x-y);
console.log(x*y);
console.log(x/y);
console.log(x%y);
console.log(x%z);
console.log(x**y);
----------------------
	+ positive
        - negative
var x = +10;
var y = -2;
console.log(x);
console.log(y);
----------------------
z = x + y;
    x + y ----> arithmetic expression
    x y ----> operands
    + -------> operator
    binary operator 
    unary operator
-------------------------
   ++    increment / decrement (pre/post)
   --

var x = 10;
var y = ++x; // increment first , assign later
console.log(x + '  ' + y);
------------------------------
var x = 10;
var y = --x; // decrement first , assign later
console.log(x + '  ' + y);
------------------------------
var x = 10;
var y = x--; //  assign first ,  decrement later
console.log(x + '  ' + y);
------------------------------
var x = 10;
var y = x++; //  assign first ,  increment later
console.log(x + '  ' + y);
------------------------------
short-cut operators
	+=
        -=
        *=
        /=
        %=

var x = 10;
//x = x + 2;
//x = 10 +2;
//x = 12;
x += 2;
console.log(x);
-------------------
var x = 10;
//x = x - 2;
x -= 2;
console.log(x);
--------------------
var x = 10;
//x = x * 2;
x *= 2;
console.log(x);
-------------------
var x = 10;
//x = x / 2;
x /= 2;
console.log(x);
--------------------
var x = 10;
//x = x % 2;
x %= 2;
console.log(x);
--------------------
relative operators - comparison 
------------------
	>
        <
        >=
        <=
        ==
        ===
        !=
Note: always the return value of a valid relative expression is boolean (true / false)
var x = 10;
var y = 2;
var z = 10;
console.log(x>y);
console.log(x>z);
console.log(x>=z);

console.log(x<y);
console.log(x<z);
console.log(x<=z);

console.log(x == y);
console.log(x != y);
console.log(x == z);
console.log(x != z);
------------------------------------
var x = 10;
var y = 10;
var z = '10';
var a = 'ashokit';
console.log(x + ' ' + typeof(x) + '  ' + y +'  '+typeof(y) + '  ' + (x==y));
console.log(x + ' ' + typeof(x) + '  ' + z +'  '+typeof(z) + '  ' + (x==z));
console.log(x + ' ' + typeof(x) + '  ' + a +'  '+typeof(a) + '  ' + (x==a));
console.log(x + ' ' + typeof(x) + '  ' + z +'  '+typeof(z) + '  ' + (x===z));
-------------------------------------------------------------------------------
console.log(true == false);
console.log(true != false);
console.log(false == false);
console.log(true == true);
---------------------------
console.log(true == false);
console.log(true != false);
console.log(false == false);
console.log(true == true);
----------------------------
console.log(true == 1);
console.log(false == 0);
console.log(true + 1);
console.log(true + true);
console.log(true - true);
console.log(true - false);
---------------------------------------
logic operators 
	&&  and
	||  or
	!   not
---------------------------------------
         &&
         ||
         - used to join multiple conditions together as one unit
         &&
           -returns true, when all the joined condition's result is true
           cond1 && cond2 && cond3 && ......condN
           -while evaluating the conditions, if any condition's result is false, no need to evaluate the remaining conditions.

console.log(true && true);
console.log(true && false);
console.log(false && true);
console.log(false && false);
true
false
false
false
----------------------------
	||
	- used to join multiple conditions together as one unit
         ||
           -returns true, when at least one condition's result is true
           cond1 || cond2 || cond3 || ......condN
           -while evaluating the conditions, if any one condition's result is true, no need to evaluate the remaining conditions.

console.log(true || true);
console.log(true || false);
console.log(false || true);
console.log(false || false);
true
true 
true 
false
------------------------------
!   not
	- it returns the opposite of the result.

console.log(true );
console.log(false);
console.log(!true);
console.log(!false);
true
false
false
true 
--------------------------------------
check this
---------
console.log(1 && 1);
console.log(1 && 0);
console.log(0 && 1);
console.log(0 && 0);
1
0
0
0
-----------------------
console.log(1 && true);
console.log(1 && false);
console.log(0 && true);
console.log(0 && false);
true
false
0
0
-------------------------
console.log(!1);
console.log(!0);
false
true
-----------------------
console.log(!-9);
console.log(!9);
console.log(!6);
console.log(!0)
------------------------
ternary operator :
	? :
-----------------------
control structures :
	- used to control the flow of execution among the statements of the program.

console.log('Good Morning');
console.log('Good Afternoon');
console.log('Good Evening');
Good Morning
Good Afternoon
Good Evening  
-----------------------------
cs are two types
	a.non-iterative 
	b.iterative - loops
	
a.non-iterative 
	-used to select one or more statements to execute or to skip them from execution based on a condition.

	1.simple if - only option
         if(condition)
         {
		// true logic
         }


        2.if..else - two options
        if(condition)
        {
             // true logic
        }
        else
        {
           // false logic
        }
     
        3.if..else if...else if....[else]   - ladder  - more than two options
        if(condition1)
        {
           // true logic
        }
        else if(condtion2)
        {
             // true logic
        }
        else if(condition3)
        {
             // true logic
        }
        --------------------
        --------------------
        --------------------
        [else
        {
           // logic - executes when all the above condition's result is false
        }]

------------------------
var x = 10;
var y = 10;
if(x<y) // 10<10 - > false
{
    console.log(x +' is less than ' + y);
}
else if(x>y) // 10>10 -> false
{
    console.log(x + ' is greater than ' + y);
}
else 
{
    console.log(x + ' is equal to ' + y);
}

--------------------------------------------
var x = 10;
var y = 10;
if(x<y) // 10<10 - > false
{
    console.log(x +' is less than ' + y);
}
else if(x>y) // 10>10 -> false
{
    console.log(x + ' is greater than ' + y);
}
else if(x == y)
{
    console.log(x + ' is equal to ' + y);
}

-------------------------------------------------
switch(variable/other)
{
	case value1:
             // logic
             break;
        case value2:
             //logic
             break;
        case value3:
             //logic
             break;
         -----------
         -----------
         -----------
         -----------
         default:
            //logic - executed when no case value is matched with switch variable's value
            break;
}
----------------
var UserType="employee";
switch(UserType)
{
    case "customer": // if(UserType=='customer')
        console.log('load customer menu');
        break;
    case "employee":
        console.log('load employee menu');
        break;
    case 'admin':
        console.log('load admin menu');
        break;
    case 'guest':
        console.log('load guest menu');
        break;
    
}
--------------------
var UserType="vendor";
switch(UserType)
{
    case "customer": // if(UserType=='customer')
        console.log('load customer menu');
        break;
    case "employee":
        console.log('load employee menu');
        break;
    case 'admin':
        console.log('load admin menu');
        break;
    case 'guest':
        console.log('load guest menu');
        break;
    default:
        console.log('invalid usertype ...check once');
        break;
}
-----------------------------------
var UserType="Customer";
UserType = UserType.toLowerCase();
switch(UserType)
{
    case "customer": // if(UserType=='customer')
        console.log('load customer menu');
        break;
    case "employee":
        console.log('load employee menu');
        break;
    case 'admin':
        console.log('load admin menu');
        break;
    case 'guest':
        console.log('load guest menu');
        break;
    default:
        console.log('invalid usertype ...check once');
        break;
}
------------------------------------------------------
var v = 89;
switch(true)
{
    case v>=90: 
        console.log('A+');
        break;
    case v>=80: 
        console.log('A');
        break;
    case v>=70:
        console.log('B');
        break;
    case v>=60:
        console.log('C');
        break;
    case v>=50:
        console.log('D');
        break;
    case v>=35:
        console.log('E');
        break;
    default:
        console.log('F');
        break;
}
-----------------------------------------------------
iterative cs - loops:
	a.while
	b.do..while
	c.for

        d.for..in

	-used to execute one or more statements again and again based on a condition
	-write once use many times
        -avoids duplication of code
        -re-usability

declaration and initialization of looping variable
condition on looping variable's value
change in the looping variable's value
----------------------
var i =1;
while(i<=6)
{
    console.log(i + ' inside while ' + (i<=6));
    i = i +1;
}
console.log(i + ' outside while ' + (i<=6));
1 inside while true
2 inside while true  
3 inside while true  
4 inside while true  
5 inside while true  
6 inside while true  
7 outside while false
--------------------------
var i =11;
while(i<=6)
{
    console.log(i + ' inside while ' + (i<=6));
    i = i +1;
}
console.log(i + ' outside while ' + (i<=6));
11 outside while false
--------------------------------------
var i =1;
do
{
    console.log(i + ' inside while ' + (i<=6));
    i = i +1;
}while(i<=6);
console.log(i + ' outside while ' + (i<=6));
--------------------------------------------------
var i =11;
do
{
    console.log(i + ' inside while ' + (i<=6));
    i = i +1;
}while(i<=6);
console.log(i + ' outside while ' + (i<=6));
11 inside while false
12 outside while false
------------------------------------------
var i;
for(i =1;i<=6;i = i +1)
{
    console.log(i + ' inside for ' + (i<=6));
}
console.log(i + ' outside for ' + (i<=6));
1 inside for true
2 inside for true  
3 inside for true  
4 inside for true  
5 inside for true  
6 inside for true  
7 outside for false
------------------------------------------------
var i;
for(i =11;i<=6;i = i +1)
{
    console.log(i + ' inside for ' + (i<=6));
}
console.log(i + ' outside for ' + (i<=6));
11 outside for false
--------------------------------
var i =1;
for(;i<=6;)
{
    console.log(i + ' inside for ' + (i<=6));
    i = i +1;
}
console.log(i + ' outside for ' + (i<=6));
-------------------------------------------
var i =1;
for(;;)
{
    console.log(i + ' inside for ' + (i<=6));
    i = i +1;
}
console.log(i + ' outside for ' + (i<=6)); // unreachable code

----------------------------------------------
var i =1;
for(;;)
{
    console.log(i + ' inside for ' + (i<=6));
    if(i==6)
    {
        break;
    }
    i = i +1;
}
console.log(i + ' outside for ' + (i<=6));
1 inside for true
2 inside for true 
3 inside for true 
4 inside for true 
5 inside for true 
6 inside for true 
6 outside for true
------------------------------------------
for...in --- collections - 
	-array 
	-is a collection of values
	-*same type or can be different type also (primitive/abstract) or arrays 
	-stored in continious memory location 
	-each value is identified by their position called index
	-where that index value starts with zero and ends with array size minus one
        -*index is number,can be string also
        - negative index is not allowed
	-for example if array is created with a size 10 then
		index value starts with 0 and ends with 9
	-to read value from array
		arrayname[index]
	-to assign a value 
		arrayname[index] =value;

array creation 
manage array using array methods

array creation 
	1.using []
	2.using Array() constructor

var arrayname = [];  // empty array

var arrayname = [v1,v2,v3,v4,......vN]; // array with values
		
var marks = [88,99,33,90,11,34,56,33,58,19];
console.log(marks[0]);
console.log(marks[1]);
// to read
console.log("using for: ");
for(i=0;i<10;i++)
{
    console.log(marks[i])
}
---------------------------
var marks = [88,99,33,90,11,34,56,33,58,19];
console.log(marks[0]);
console.log(marks[1]);
// to read
console.log("using for in: ");
for(i in marks)
{
    console.log(i  + "  " + marks[i]);
}
------------------------------------------------
//var marks = [88,99,33,90,11,34,56,33,58,19];
var marks = [88,99,33,90,11,34];
console.log(marks[0]);
console.log(marks[1]);
// to read
console.log("using for in: ");
for(i in marks)
{
    console.log(i  + "  " + marks[i]);
}
----------------------------------------------
var Product = [9001,'Apple','1Kg',199.00,true];
console.log(Product);
--------------------------------------
var Product = []; // empty array
console.log(Product);
--------------------------------------
// array with multiple values
var Product = Array(9009,'Toor Dal','1kg',299.00,true);
console.log(Product);
--------------------------------------
// array with single value - 
// becomes array size not array content
var Product = Array(9);
console.log(Product);
console.log('size ' + Product.length);
-----------------------------------------
// array with single value - 
var Product = [9];
console.log(Product);
console.log('size ' + Product.length);
[ 9 ]
size 1
--------------------------------------------
var Product = 
[ 9001,
 'Toor/Arhar Dal',
 'bb Popular',
 'Veg',
 true,
 '10000428_17-bb-popular-toorarhar-dal.jpg',
 '500g',
 '1kg',
 '2kg',
 140,
 275,
 549,
 38,
 48,
 44,
 87.5,
 144,
 309,
 true,
 true,
 true
];
console.log(Product);
console.log('size ' + Product.length); // size 21
------------------------------------------------------
Product
	ProductId:single value
        ProductName : sv
        Brand : sv
        Type : sv
        IsActive: sv
        ImagePath :sv
        Quantity : multiple values
        Mrp : multiple values
        Offer:multiple values
        SalePrice: multiple values
        QStatus:multiple values
---------------------------------------
var Quantity = ['500g','1kg','2kg'];
var Mrp = [140,275,549];
var Offers = [38,48,44];
var SalePrice = [87.5,144,309];
var QStatus = [true,true,true];
var Product = 
[ 9001,
 'Toor/Arhar Dal',
 'bb Popular',
 'Veg',
 true,
 '10000428_17-bb-popular-toorarhar-dal.jpg',
 Quantity,
 Mrp,
 Offers,
 SalePrice,
 QStatus
 ];
console.log(Product);
console.log('size ' + Product.length); 
console.log('Product Id : ' + Product[0]);
console.log('Name : ' + Product[1]);
console.log('Quantity :' + Product[6]);
console.log('Quantity :' + Product[6][0]);
console.log('Quantity :' + Product[6][1]);
console.log('Quantity :' + Product[6][2]);
--------------------------------------------------
21st
-----
var Quantity = Array('500g','1kg','2kg');
var Mrp = Array(140,275,549);
var Offers = Array(38,48,44);
var SalePrice = Array(87.5,144,309);
var QStatus = Array(true,true,true);
var Product = 
[ 
  9001,
 'Toor/Arhar Dal',
 'bb Popular',
 'Veg',
 true,
 '10000428_17-bb-popular-toorarhar-dal.jpg',
 Quantity,
 Mrp,
 Offers,
 SalePrice,
 QStatus
 ];
console.log(Product);
console.log('size ' + Product.length); 
console.log('Product Id : ' + Product[0]);
console.log('Name : ' + Product[1]);
console.log('Quantity :' + Product[6]);
console.log('Quantity :' + Product[6][0]);
console.log('Quantity :' + Product[6][1]);
console.log('Quantity :' + Product[6][2]);
---------------------------------------------
// try to a value from non-existing location
var marks = [99,38,68,39,44,96];
console.log(marks);
console.log(marks[0]);
console.log('size  ' + marks.length);
// try to a value from non-existing location
console.log(marks[9]); // undefined
-------------------------------------------------
// assigning a value to a non-existing location
// the given new location is created 
var marks = [99,38,68,39,44,96];
console.log(marks);
console.log(marks[0]);
console.log('size  ' + marks.length);
marks[0] = 100;
console.log(marks[0]); 
marks[9] = 39;
console.log('size : ' + marks.length);
console.log(marks);
[ 100, 38, 68, 39, 44, 96, <3 empty items>, 39 ]
--------------------------------------------------
// array is dynamic
var marks = [];
console.log(marks);
console.log('size ' + marks.length);
marks[0] = 88;
console.log(marks);
console.log('size ' + marks.length);
marks[1] = 99;
console.log(marks);
console.log('size ' + marks.length);
marks[2] = 44;
console.log(marks);
console.log('size ' + marks.length);
-------------------------------------
var data = Array(0);
console.log(data);
console.log(data.length);
--------------------------
var data = Array();
console.log(data);
console.log(data.length);
---------------------------
//RangeError: Invalid array length
var data = Array(-3);
console.log(data);
console.log(data.length);
----------------------------
var Product = [];
console.log(Product + '   ' + Product.length);
Product['ProductId'] = 9009;
Product['Name'] = 'Organic Indian Toor Dal';
Product['Quantity'] = '2Kg';
Product['Price'] = 399;
console.log(Product);
console.log(Product + '   ' + Product.length);
console.log(Product[0]); // undefined
console.log(Product['ProductId']);
console.log(Product['Name']);
console.log(Product['Quantity']);
console.log(Product['Price']);
--------------------------------
array methods
-------------
	a.creation
	b.managing the array values
		1.add
		2.remove
		3.search
		4.sort
		5.other

to add and remove
-----------------
	push() - used to append the given value/values/array at the end of the array.
                 it returns new size
        unshift() -used to insert the given value/values/array at the top of the array.
                 it returns new size

        pop() - used to remove and return the value from the end of an array.
              - when pop is applied on an empty array , it returns undefined.

        shift() - used to remove and return the value from the top of an array.
              - when shift is applied on an empty array , it returns undefined.
        splice() - used to insert/remove/replace
        includes() - searches for the given value , from the given index(starting index for search)
                     if found returns true, not found returns false.

// array methods - push with single value
var marks = [99,39,29,49,56,79];
console.log(marks.length);
console.log(marks.push(69));
console.log(marks);
[
    99, 39, 29, 49,
    56, 79, 69     
  ]
------------------------
// array methods - push with multiple value
var marks = [99,39,29,49,56,79];
console.log(marks.length);
console.log(marks.push(69,19,29));
console.log(marks.length);
console.log(marks);
[
    99, 39, 29, 49, 56,
    79, 69, 19, 29     
  ]
-------------------------
// array methods - push with array
var marks = [99,39,29,49,56,79];
console.log(marks.length);
console.log(marks.push([69,19,29]));
console.log(marks.length);
console.log(marks);
[ 99, 39, 29, 49, 56, 79, [ 69, 19, 29 ] ]
--------------------------------------------
22nd 
----
var marks = [99,39,29,49,56,79];
// unshift with single value
console.log('size before:' + marks.length);
console.log(marks.unshift(69));
console.log('size after:' + marks.length);
console.log(marks);
[
    69, 99, 39, 29,
    49, 56, 79
  ]
-----------------------------------------------
var marks = [99,39,29,49,56,79];
// unshift with multile values
console.log('size before:' + marks.length);
console.log(marks.unshift(69,33,19));
console.log('size after:' + marks.length);
console.log(marks);
[
    69, 33, 19, 99, 39,
    29, 49, 56, 79
  ]
--------------------------------------------
var marks = [99,39,29,49,56,79];
// unshift with array
console.log('size before:' + marks.length);
console.log(marks.unshift([69,33,19]));
console.log('size after:' + marks.length);
console.log(marks);
[ [ 69, 33, 19 ], 99, 39, 29, 49, 56, 79 ]
-------------------------------------------
var marks = [99,39,29,49,56,79];
// pop with array
console.log('size before:' + marks.length);
console.log(marks.pop()); // 79
console.log('size after:' + marks.length);
console.log(marks);
[ 99, 39, 29, 49, 56 ]
-----------------------------
var marks = [99,39,29,49,56,79];
// shift with array
console.log('size before:' + marks.length);
console.log(marks.shift());
console.log(marks);
console.log(marks.shift());
console.log(marks.shift());
console.log(marks.shift());
console.log(marks.shift());
console.log(marks.shift());
console.log('size after:' + marks.length);
console.log(marks);
console.log(marks.shift()); // undefined
size before:6
99
[ 39, 29, 49, 56, 79 ]
39
29
49
56
79
size after:0
[]
undefined
--------------------------------------------
var marks = [99,39,29,49,56,79];
console.log('size before:' + marks.length);
// splice as insert method - insert the given value(3rd param) at given index (1st parameter)
var result =  marks.splice(0,0,69);
console.log('size after:' + marks.length);
console.log(marks);
console.log(result);
size before:6
size after:7
[
  69, 99, 39, 29,
  49, 56, 79
]
[]
------------------------------
var marks = [99,39,29,49,56,79];
console.log('size before:' + marks.length);
// splice as insert method - insert the given value(3rd param) at given index (1st parameter)
var result =  marks.splice(2,0,69);
console.log('size after:' + marks.length);
console.log(marks);
console.log(result);
size before:6
size after:7
[
  99, 39, 69, 29,
  49, 56, 79
]
[]
--------------------------------
var marks = [99,39,29,49,56,79];
console.log('size before:' + marks.length);
// splice as insert method - insert the given value(3rd param) at given index (1st parameter)
var result =  marks.splice(2,0,699,199,299,399);
console.log('size after:' + marks.length);
console.log(marks);
console.log(result);
size before:6
size after:10
[
   99, 39, 699, 199, 299,
  399, 29,  49,  56,  79
]
[]
----------------------------------
var marks = [99,39,29,49,56,79];
console.log('size before:' + marks.length);
// splice as insert method - insert the given value(3rd param) at given index (1st parameter)
var result =  marks.splice(2,0,[699,199,299,399]);
console.log('size after:' + marks.length);
console.log(marks);
console.log(result);
size before:6
size after:7
[ 99, 39, [ 699, 199, 299, 399 ], 29, 49, 56, 79 ]
[]
---------------------------------------------------
//splice as  a remove
--------------------
var marks = [99,39,29,49,56,79];
console.log('size before:' + marks.length);
// splice as remove/delete method - deletes the specified number of values(2nd param) 
// from the  given index (1st parameter)
var deletedValues =  marks.splice(1,3);
console.log('size after:' + marks.length);
console.log(marks);
console.log(deletedValues);
size before:6
size after:3
[ 99, 56, 79 ]
[ 39, 29, 49 ]
---------------------------------------
replace - remove + insert at same place
---------------------------------------
var marks = [99,39,29,49,56,79];
console.log('size before:' + marks.length);
// splice as replace method 
var deletedValues =  marks.splice(0,1,69);
console.log('size after:' + marks.length);
console.log(marks);
console.log(deletedValues);
[ 69, 39, 29, 49, 56, 79 ]
[ 99 ]
----------------------------------------
includes()
----------
var marks = [99,39,29,49,9,56,79,44,9,0,-2,18,55,9,26,38,59];
// searches for a given value from starting - 0th index
console.log(marks.includes(199)); // false
---------------------------------------------
var marks = [99,39,29,49,9,56,79,44,9,0,-2,18,55,9,26,38,59];
// searches for a given value from starting - 0th index
console.log(marks.includes(39)); // true
----------------------------------------------
var marks = [99,39,29,49,9,56,79,44,9,0,-2,18,55,9,26,38,59];
// searches for a given value from starting - 0th index
console.log(marks.includes(9));  //searches for 9 from 0th index - 4th
----------------------------------------------------------
var marks = [99,39,29,49,9,56,79,44,9,0,-2,18,55,9,26,38,59];
// searches for a given value from starting - 0th index
console.log(marks.includes(9,5));  //searches for 2nd 9 from 5th index - 8th
//true
-------------------------------------------------
var marks = [99,39,29,49,9,56,79,44,9,0,-2,18,55,9,26,38,59];
// searches for a given value 
console.log(marks.includes(9,9));  //searches for 3rd 9 from 9th index - 13th
//true
--------------------------------------------------------
var marks = [99,39,29,49,9,56,79,44,9,0,-2,18,55,9,26,38,59];
// searches for a given value 
console.log(marks.includes(9,14));  //searches for 4th 9 from 14th index - no
//false
-----------------------------------------------------------
23rd
----
marks.map()
marks.filter()
marks.findIndex()
marks.sort()
------------
function :
	- a collection one or more statements indentified by a name
	- in the program where ever that functionality is required , it is referred by it's name.
	- write once use many times in many places.
	- to function we can pass values 
	- a function may return value

types of functions in javascript

1.named function
2.un-named function
3.arrow function

cases based on input parameters and arguments
--------------------------------------------
case 1 : ip and arguments are equal
function Add(x, y) // x y - inpuparameters
{
    console.log(x+y);
}
Add(10,20); // 10 20 - arguments
----------------------------------
case2: arguments are more than ip
function Add(x, y) // x - 10 y - 20 inpuparameters
{
    console.log(x+y);
}
Add(10,20,30,40); // overflow of arguments
-----------------------------------------
case 3: arguments are less than ip
function Add(x, y) // x - 10 y - ? inpuparameters
{
    console.log(x); // 10
    console.log(y); // undefined
    console.log(x+y); // 10 + undefined=>NaN
}
Add(10); 
-------------------------------
based on type of ip or type of arguments
---------------------------------------
function Add(x, y) 
{
    
    console.log(x+y); 
}
Add(10,20); // number
Add(299.29,39.49); // number
Add("ashok","it"); // string
Add(true,true); // boolean
Add("dotnet",9); // string number
Add([1234],[5,6,7,8]); //array
// on function responding for all types of calling statements
------------------------------
function Add(x, y) 
{
    
    console.log(x+y); 
}
Add(10,20);
var Sum = Add; 
console.log(Sum + '');
Sum(30,90);
Note: function can be assigned as like a value  to the variable
----------------------------------------------------------------
function f1()
{
    console.log('i am function f1');
}
function f2()
{
    console.log('i am function f2');
}
function f3(x,y)
{
    console.log('i am from f3');
    x();
    y();
}
f3(f1,f2);  // call back functions
Note: a function which is passed as an argument is called as call back function
-------------------------------------------------------------------------------
Note: a function which is taking other as input(argument) or returning a function is called HOF.
HOF : Higher Order Function
function f1()
{
    console.log('i am a function f1');
    function f2()
    {
        console.log('i am f2 created inside the f1');
    }
    return f2;
}

var f3 = f1(); // f3 = f2;
f3();
-------------------------------------------------
function Add(x,y)
{
    console.log('I am function Add ' + (x+y));
}
Add(10,20);

function Sum(x) // x = Add
{
    x(100,200);
}

Sum(Add); // Add is assigned to x
-------------------------------------
Note: a named function can be assigned a value to a variable
      named function's name loses it's identity
var Total = function Add(x,y)
            {
                console.log('I am function Add ' + (x+y));
            }

Total(10,20);
//Add(100,200); // ReferenceError: Add is not defined
---------------------------------------------------------
var Total = function (x,y)
            {
                console.log('I am a unnamed function  ' + (x+y));
            }

Total(10,20);
------------------------------------------------------------
// arrow function 
var Total = (x,y)=>  // input area parameters goes to functional body
            {
                console.log('I am a arrow function  ' + (x+y));
            }  // functional body

Total(10,20);
------------------------------
var courses = ['java','csharp','go','algol','cobol','fotran','python','c++','pascal','vb','fsharp'];
console.log(courses);
courses.sort();
console.log('after sort: ');
console.log(courses);
after sort: 
[
  'algol',  'c++',
  'cobol',  'csharp',
  'fotran', 'fsharp',
  'go',     'java',
  'pascal', 'python',
  'vb'
]
-------------------------------
var courses = ['java','csharp','Go','algol','Cobol','fotran','python','c++','pascal','vb','Fsharp'];
console.log(courses);
courses.sort();
console.log('after sort: ');
console.log(courses);
after sort:
[
  'Cobol',  'Fsharp',
  'Go',     'algol',
  'c++',    'csharp',
  'fotran', 'java',
  'pascal', 'python',
  'vb'
]
--------------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
marks.sort(); // sort logic sutiable for strings not for numbers
console.log(marks);
[
    -2,  0, 18, 18, 23, 26, 29,
    29, 44, 49, 51, 59,  6, 79,
     9,  9,  9
  ]
--------------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
//marks.sort(); // sort logic sutiable for strings not for numbers
console.log(marks);
marks.sort(Check)
function Check(x,y)
{
    return x - y;
}
console.log('after sort : '+ marks);
[
    29, 23, 29, 49,  9,  6, 79,
    44,  9,  0, -2, 18, 51,  9,
    26, 18, 59
  ]
  after sort : -2,0,6,9,9,9,18,18,23,26,29,29,44,49,51,59,79
----------------------------------------------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
//marks.sort(); // sort logic sutiable for strings not for numbers
console.log(marks);
marks.sort(function Check(x,y)
{
    return x - y;
})
console.log('after sort : '+ marks);
--------------------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
//marks.sort(); // sort logic sutiable for strings not for numbers
console.log(marks);
marks.sort(function (x,y)
{
    return x - y;
})
console.log('after sort : '+ marks);
--------------------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
//marks.sort(); // sort logic sutiable for strings not for numbers
console.log(marks);
marks.sort((x,y)=>
{
    return x - y;
})
console.log('after sort : '+ marks);
-------------------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
//marks.sort(); // sort logic sutiable for strings not for numbers
console.log(marks);
marks.sort((x,y)=>
{
    return y - x;
})
console.log('after sort : '+ marks);
[
    29, 23, 29, 49,  9,  6, 79,
    44,  9,  0, -2, 18, 51,  9,
    26, 18, 59
  ]
  after sort : 79,59,51,49,44,29,29,26,23,18,18,9,9,9,6,0,-2
---------------------------------------------------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
var fresult = marks.filter(Check)
function Check(v)
{
    return v<35;
}
console.log(fresult);
[
    29, 23, 29,  9, 6,
     9,  0, -2, 18, 9,
    26, 18
  ]
//Check(29) 29<35 - true
//Check(23) 23<35 - true
//Check(29) 29<35 - true
//Check(49) 49<35 - false
----------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
var presult = marks.filter(Check)
function Check(v)
{
    return v>=35;
}
console.log(presult);
//[ 49, 79, 44, 51, 59 ]
-----------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
var presult = marks.filter((v)=>
{
    return v>=35;
})
console.log(presult);
--------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
var oresult = marks.filter((v)=>
{
    return v%2 ==1;
})
console.log(oresult);
[
    29, 23, 29, 49,  9,
    79,  9, 51,  9, 59
]
----------------------------
var marks = [29,23,29,49,9,6,79,44,9,0,-2,18,51,9,26,18,59];
var eresult = marks.filter((v)=>
{
    return v%2 ==0;
})
console.log(eresult);
[
    6, 44,  0, -2,
   18, 26, 18
 ]
----------------------------------
var Products = ['apple','toor dal','loose rice','mango','chana dal','loose sugar','moong dal','potato','cherry'];
 var dals = Products.filter((name)=>
 {
     return name.endsWith('dal')
 });
 console.log(dals);
 [ 'toor dal', 'chana dal', 'moong dal' ]
------------------------------------------