index-js-21.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    

    How to declare variable in javascript?

Variables in JavaScript can be declared using the "var", "let", or "const" keywords:

"var" : Declares a variable with function scope (can be accessed within the function it was declared).
"let" : Declares a variable with block scope (can be accessed within the block it was declared and in nested blocks).
"const" : Declares a constant variable with block scope (cannot be reassigned after initial value is set).

Syntax:

var variableName = value;

var name = "John Doe";
var age = 30;
var isMarried = true;

let variableName = value;

let country = "United States";
let city = "New York";
let zipCode = 10001;

const variableName = value;

const PI = 3.14;
const NUMBER_OF_STATES = 50;
const COMPANY_NAME = "Acme Inc.";


21-3 Check even and odd number using function////////////////////////////////////


function isEven(number){
    const remainder = number % 2;
    console.log(remainder);
}

isEven(48);

terminal-
0
so remainder 0 means even number


function isEven(number){
    const remainder = number % 2;
    console.log(remainder);
}

isEven(303);
terminal-
1
so remainder 1 means odd number


function isEven(number){
    const remainder = number % 2;
    if(remainder === 0){
        console.log('number is even')
    }
    else{
        console.log('number is odd');
    }
}

isEven(48);

terminal-
number is even


function isEven(number){
    const remainder = number % 2;
    if(remainder === 0){
        console.log('number is even')
    }
    else{
        console.log('number is odd');
    }
}

isEven(303);

terminal-
number is odd


function isEven(number){
    const remainder = number % 2;
    if(remainder === 0){
        console.log('number is even')
    }
    else{
        console.log('number is odd');
    }
}

isEven(303);
isEven(1280);

terminal-
number is odd
number is even


function isEven(number){
    const remainder = number % 2;
    if(remainder === 0){
        return true;
    }
    else{
        return false;
    }
}

const myNumberIsEven = isEven(303);
console.log(myNumberIsEven);
const herNumberIsEven = isEven(202);
console.log(herNumberIsEven);

terminal-
false
true


function isEven(number){
    const remainder = number % 2;
    if(remainder === 0){
        return true;
    }
    else{
        return false;
    }
}

const myNumberIsEven = isEven(303);
const herNumberIsEven = isEven(202);
console.log(myNumberIsEven);
console.log(herNumberIsEven);

terminal-
false
true


21-4 Check whether a year is a Leap Year or not (simplified way)/////////////////////

function isLeapYear (year){
    const remainder = year % 4;
    if(remainder === 0){
        console.log('year is leap year', year);
    }
    else{
        console.log('year is not a leap year', year); 
    }
}

isLeapYear(1933);

terminal-
year is not a leap year 1933


function isLeapYear (year){
    const remainder = year % 4;
    if(remainder === 0){
        console.log('year is leap year', year);
    }
    else{
        console.log('year is not a leap year', year); 
    }
}

isLeapYear(1933);
isLeapYear(1960);

terminal-
year is not a leap year 1933
year is leap year 1960 


function isLeapYear (year){
    const remainder = year % 4;
    if(remainder === 0){
        return true;
    }
    else{
        return false; 
    }
}

const isFirstYearLeapYear = isLeapYear(1933);
console.log('first year', isFirstYearLeapYear);
const isSecondYearLeapYear = isLeapYear(1960);
console.log('second year', isSecondYearLeapYear);

terminal-
first year false
second year true  


function isLeapYear (year){
    const remainder = year % 4;
    if(remainder === 0){
        return true;
    }
    {
        return false; 
    }
}

const isFirstYearLeapYear = isLeapYear(1933);
console.log('first year', isFirstYearLeapYear);
const isSecondYearLeapYear = isLeapYear(1960);
console.log('second year', isSecondYearLeapYear);

terminal-
first year false
second year true  


21-5 Calculate Sum of all numbers of an array////////////////////////////////////


function getSumOfAnArray(numbers){
    let sum = 0;
    for(let i = 0; i < numbers.length; i ++){
        const index = i;
        const element = numbers[index];
        sum = sum + element;
        console.log(index, element, sum);
    }
    return sum;
}

const myNumbers = [12, 65, 45, 78, 32, 45, 91];
getSumOfAnArray(myNumbers);


terminal-
0 12 12
1 65 77
2 45 122
3 78 200
4 32 232
5 45 277
6 91 368


21-6 Get Odd Numbers of an array and get odd Sum of an array/////////////////////////////


function getSumOfAnArray(numbers){
    let sum = 0;
    for(let i = 0; i < numbers.length; i ++){
        const index = i;
        const element = numbers[index];
        sum = sum + element;
    }
    return sum;
}

function getSumOddNumbersOfAnArray(numbers){
    for(let i = 0; i < numbers.length; i++)
    console.log(i);
}

const myNumbers = [12, 65, 45, 78, 32, 45, 91];
getSumOddNumbersOfAnArray(myNumbers);
getSumOfAnArray(myNumbers);


terminal-
1
2
3
4
5
6


function getSumOfAnArray(numbers){
    let sum = 0;
    for(let i = 0; i < numbers.length; i ++){
        const index = i;
        const element = numbers[index];
        sum = sum + element;
    }
    return sum;
}

function getSumOddNumbersOfAnArray(numbers){
    for(let i = 0; i < numbers.length; i++){
        const index = i;
        const element = numbers[index];
        console.log(index, element);
    }
}

const myNumbers = [12, 65, 45, 78, 32, 45, 91];
getSumOddNumbersOfAnArray(myNumbers);
getSumOfAnArray(myNumbers);

terminal-
0 12
1 65
2 45
3 78
4 32
5 45
6 91


function getSumOfAnArray(numbers){
    let sum = 0;
    for(let i = 0; i < numbers.length; i ++){
        const index = i;
        const element = numbers[index];
        sum = sum + element;
    }
    return sum;
}

function getSumOddNumbersOfAnArray(numbers){
    for(let i = 0; i < numbers.length; i++){
        const index = i;
        const element = numbers[index];
        if(element % 2 === 0)
        console.log(index, element);
    }
}

const myNumbers = [12, 65, 45, 78, 32, 45, 91];
getSumOddNumbersOfAnArray(myNumbers);
getSumOfAnArray(myNumbers);


terminal-
0 12
3 78
4 32


function getSumOfAnArray(numbers){
    let sum = 0;
    for(let i = 0; i < numbers.length; i ++){
        const index = i;
        const element = numbers[index];
        sum = sum + element;
    }
    return sum;
}

function getSumOddNumbersOfAnArray(numbers){
    for(let i = 0; i < numbers.length; i++){
        const index = i;
        const element = numbers[index];
        if(element % 2 !== 0)
        console.log(index, element);
    }
}

const myNumbers = [12, 65, 45, 78, 32, 45, 91];
getSumOddNumbersOfAnArray(myNumbers);
getSumOfAnArray(myNumbers);


terminal-
1 65
2 45
5 45
6 91


function getSumOfAnArray(numbers){
    let sum = 0;
    for(let i = 0; i < numbers.length; i ++){
        const index = i;
        const element = numbers[index];
        sum = sum + element;}
    return sum; 
}

function getOddNumbersOfAnArray(numbers){
    const oddNumbers = [];
    for(let i = 0; i < numbers.length; i++){
        const index = i;
        const element = numbers[index];
        if(element % 2 !== 0){
        console.log(index, element);
        oddNumbers.push(element);
    }
    }
    return oddNumbers;
}

const myNumbers = [12, 65, 45, 78, 32, 45, 91];
const oddNumbers = getOddNumbersOfAnArray(myNumbers);
console.log(oddNumbers);
getSumOfAnArray(myNumbers);


terminal-
1 65
2 45
5 45
6 91
[ 65, 45, 45, 91 ]


function getSumOfAnArray(numbers){
    let sum = 0;
    for(let i = 0; i < numbers.length; i ++){
        const index = i;
        const element = numbers[index];
        sum = sum + element;}
    return sum; }

function getOddNumbersOfAnArray(numbers){
    const oddNumbers = [];
    for(let i = 0; i < numbers.length; i++){
        const index = i;
        const element = numbers[index];
        if(element % 2 !== 0){
        console.log(index, element);
        oddNumbers.push(element);}
    }
    return oddNumbers;
}

const myNumbers = [12, 65, 45, 78, 32, 45, 91];
const oddNumbers = getOddNumbersOfAnArray(myNumbers);
console.log(oddNumbers);
const oddNumberSum = getSumOfAnArray(oddNumbers);
console.log('odd number sum', oddNumberSum);


terminal-
1 65
2 45
5 45
6 91
[ 65, 45, 45, 91 ]
odd number sum 246


21-7 Calculate Factorial of a number using for loop/////////////////////////////////////


// 1 + 2 + 3 + 4 + 5 + 6 + 7

for(let i = 1; i < 7; i++){
    console.log(i);
}


terminal-
1
2
3
4
5
6

1 + 2 + 3 + 4 + 5 + 6 + 7

let sum = 0
for(let i = 1; i < 7; i++){
    sum = sum + i;
    console.log(i, sum);
}


terminal-
1 1
2 3
3 6
4 10
5 15
6 21

1 + 2 + 3 + 4 + 5 + 6 + 7

function sumOfNumbers(number){
    let sum = 1;
    for (let i = 1; i<= number; i++){
        sum = sum + i;
        console.log(i, sum);
    }
    return sum;
}
const result = sumOfNumbers(7);
console.log(result);


terminal-
2 4
3 7
4 11
5 16
6 22
7 29
29


1 * 2 * 3 * 4 * 5 * 6 * 7 

function multiplicationOfNumbers(number){
    let result = 1;
    for(let i = 1; i<=7; i++){
        result = result * i;
    }
    return result;
}  

const result = multiplicationOfNumbers(7);
console.log(result);


terminal-
5040


21-8 Factorial using a while loop or a decrementing loop/////////////////////////


function factorial(number){
    let result = 1;
    for(let i = 1; i <= number; i++){
        result = result * i;
    }
    return result;
}

const result = factorial(9);
console.log(result);


terminal-
362880


function factorial(number){
    for(let i = number; i >= 1; i--){
        console.log(i);
    }
}

factorial(7);

terminal-
7
6
5
4
3
2
1


function factorial(number){
    let result = 1;
    for(let i = number; i >= 1; i--){
        result = result * i;
        console.log(i);
    }
}

const fact = factorial(9);
console.log('factorial of 9;', fact)

terminal-
9
8
7
6
5
4
3
2
1


function factorial(number){
    let result = 1;
    for(let i = number; i >= 1; i--){
        result = result * i;
        console.log(i);
    }
}

const number = 5;
const fact = factorial(number);
console.log('factorial of number;', fact)


terminal-
5
4
3
2
1


21-9 Module Summary and Simple JavaScript debug////////////////////////

function print(a, b, c){
    return a+2;
    return a*b;
    return b*c+a;
  }
  console.log(print(1,2,3));


</body>
</html>"# js-21" 