30Days30JavaScript Challenge by Hitesh Sir

Ankit Mishra's photo
Ankit Mishra
·

10 min read

Table of contents

Day 1: Variables and Data Types by

Activity 1: Variable Declaration

Task 1: Declaring with var

var num = 11;
console.log("Variable declared using var: " + num);

  • Uses var to declare a variable

  • Assigns a number value

  • Demonstrates basic console logging

Task 2: Declaring with let

let name1 = "Ankit";
console.log("Variable declared using let: " + name1);

  • Uses let for variable declaration

  • Assigns a string value

  • Shows difference in declaration between var and let

Activity 2: Constant Declaration

Task 3: Declaring with const

const human = true;
console.log("Variable declared using const: " + human);

  • Introduces const for constant values

  • Assigns a boolean value

  • Demonstrates that const is used for values that shouldn't change

Activity 3: Data Types

Task 4: Various Data Types

var age = 10;
var twitter = "ankitmishraexe";
var placed = false;
const details_of_person = {
  name_of_person: "Ankit Mishra",
  age: 22,
  college: "CGC",
};
const arr = ["ankit", "mishra", "is", 22, "years", "old", true];

  • Demonstrates different data types: number, string, boolean, object, array

  • Uses typeof operator to check data types

  • Shows how to create and use arrays and objects

Activity 4: Reassigning Variables

Task 5: Reassigning let Variables

let number1 = 22;
console.log("number1 is: " + number1);
number1 = 23;
console.log("number1 is: " + number1);

  • Shows that variables declared with let can be reassigned

  • Demonstrates value changing over time

Activity 5: Understanding const

Task 6: Attempting to Reassign const

const number2 = 22;
number2 = 23;  This would cause an error

  • Illustrates that const variables cannot be reassigned

  • Code is commented out to prevent runtime errors

Feature Requests

1. Variable Types Console Log

var company = "Google";
let year = 2024;
var permanent = true;

const login_credentials = {
  uername: "Ankitthegoat",
  team_id: 23553,
  location: "Hyderabad",
  passKey: 43873892,
};

for (key in login_credentials) {
  var value = login_credentials[key];
  console.log(key, value, typeof value);
}

const completeDetail = [company, year, permanent];

completeDetail.forEach((e) => {
  console.log("Value: " + e + " typeOfValue: " + typeof e);
});

  • Declares variables of different types

  • Uses object to store multiple related values

  • Demonstrates iterating over object properties

  • Shows use of arrays and the forEach method

  • Illustrates how to log both value and type of variables

2. Reassignment Demo

var password = 123498623;
console.log("Password: " + password);
password = 1234423;
console.log("Password reassigned : " + password);

const username = "@AnkitMishraexe";
console.log("Username of Twitter is : " + username);
username = "@Ankit.exe"; // This line will cause an error
console.log("Username of Twitter is changed  : " + username);

  • Demonstrates reassignment of var variables

  • Attempts to reassign a const variable, which will cause an error

  • Illustrates the difference between var/let and const in terms of reassignment

Key Concepts

  1. Variable Declaration: Using var, let, and const to declare variables.

  2. Data Types: Understanding different data types in JavaScript (number, string, boolean, object, array).

  3. Type Checking: Using the typeof operator to determine variable types.

  4. Objects: Creating and accessing object properties.

  5. Arrays: Creating and manipulating arrays.

  6. Loops: Using for...in loops and forEach method for iteration.

  7. Reassignment: Understanding which variables can be reassigned (var, let) and which cannot (const).

Output

DAY 2: Operators

Welcome to Day 2 of our JavaScript learning journey from Hitesh sir! Today, we're diving into the world of operators. Operators are essential in programming as they allow us to perform operations on variables and values. Let's explore the different types of operators in JavaScript.

1. Arithmetic Operators

Arithmetic operators are used for mathematical calculations. Here are the basic ones:

  • Addition (+)

  • Subtraction (-)

  • Multiplication (*)

  • Division (/)

  • Remainder (%)

Example:

function add(a, b) {
  console.log("Sum of the given numbers is:", a + b);
}
add(100, 827);

2. Assignment Operators

Assignment operators are used to assign values to variables. The most common ones are:

  • += (add and assign)

  • -= (subtract and assign)

Example:

var num = 5875;
num += 25;
console.log("Sum after using operator is:", num);

3. Comparison Operators

Comparison operators are used to compare two values. They include:

  • (greater than)

  • < (less than)

  • \= (greater than or equal to)

  • <= (less than or equal to)

  • \== (equal to, checks value only)

  • \=== (strict equal to, checks value and type)

Example:

function compareNumbers(a, b) {
  if (a > b) console.log(`${a} is greater than ${b}`);
  else if (a < b) console.log(`${a} is smaller than ${b}`);
  else console.log(`${a} is equal to ${b}`);
}
compareNumbers(875, 76);

4. Logical Operators

Logical operators are used to combine multiple conditions:

  • && (AND)

  • || (OR)

  • ! (NOT)

Example:

function andOperator(a, b) {
  if (a + b > 20 && a > b) {
    console.log(`Sum of ${a} and ${b} is greater than 20 and ${a} is greater than ${b}`);
  }
}
andOperator(789, 123);

5. Ternary Operator

The ternary operator is a shorthand way of writing an if-else statement:

function checkNumber(a) {
  a >= 0 ? (a == 0 ? console.log(`${a} is zero`) : console.log(`${a} is positive`)) : console.log(`${a} is negative`);
}
checkNumber(8480);

Output

DAY3: JavaScript Control Structures Practice

This repository contains JavaScript functions demonstrating various control structures and conditional logic. These exercises are designed to help beginners understand and practice if-else statements, switch cases, ternary operators, and more complex conditional checks.

If-Else Statements

1. Check Number Sign

This function checks if a number is positive, negative, or zero.

function checkNumber(a) {
  if (a > 0) console.log(`${a} is a positive number`);
  if (a < 0) console.log(`${a} is a negative number`);
  if (a == 0) console.log(`${a} is zero`);
}

Usage:

checkNumber(87218);  // Output: 87218 is a positive number
checkNumber(-218);   // Output: -218 is a negative number
checkNumber(0);      // Output: 0 is zero

2. Check Voting Eligibility

This function determines if a person is eligible to vote based on their age.

function eligibleToVote(age) {
  if (age >= 18)
    console.log("Hurrey!! Now you can vote and make the democracy Strong");
  else
    console.log(
      `Ooopsss!!! you have to wait ${18 - age} years to be eligible to VOTE!!`
    );
}

Usage:

eligibleToVote(37);  // Output: Hurrey!! Now you can vote and make the democracy Strong
eligibleToVote(3);   // Output: Ooopsss!!! you have to wait 15 years to be eligible to VOTE!!

Nested If-Else Statements

3. Find Largest Among Three Numbers

This function finds the largest number among three given numbers using nested if-else statements.

function largestAmongThree(a, b, c) {
  if (a > b) {
    if (a > c) console.log(`${a} is the Largest Among ${a} and ${b} and ${c}`);
    else console.log(`${c} is the Largest Among ${a} and ${b} and ${c}`);
  } else if (b > c)
    console.log(`${b} is the Largest Among ${a} and ${b} and ${c}`);
  else console.log(`${c} is the Largest Among ${a} and ${b} and ${c}`);
}

Switch Case

4. Determine Day of the Week

This function uses a switch case to determine the day of the week based on a number (1-7).

function WhichDay(a) {
  switch (a) {
    case 1:
      console.log("Today is MONDAY");
      break;
    case 2:
      console.log("Today is TUESDAY");
      break;
    // ... (other cases)
    case 7:
      console.log("Today is SUNDAY");
      break;
    default:
      console.log("OOOPPSSSS!!!!! Enter number between 1 to 7");
  }
}

Usage:

WhichDay(7);    // Output: Today is SUNDAY
WhichDay(875);  // Output: OOOPPSSSS!!!!! Enter number between 1 to 7

5. Assign Grade Based on Score

This function uses a switch case with ranges to assign a grade based on a score.

function assignToFun(score) {
  switch (true) {
    case score >= 80 && score <= 100:
      console.log("A");
      break;
    case score >= 70 && score < 80:
      console.log("B");
      break;
    // ... (other cases)
    default:
      console.log("F");
  }
}

Usage:

assignToFun(23);  // Output: F
assignToFun(73);  // Output: B
assignToFun(93);  // Output: A

Conditional (Ternary) Operator

6. Check if Number is Even or Odd

This function uses the ternary operator to check if a number is even or odd.

function EvenOdd(a) {
  var res = a % 2 == 0 ? "even" : "odd";
  console.log(res);
}

Usage:

EvenOdd(8578);  // Output: even

Combining Conditions

7. Check Leap Year

This function checks if a year is a leap year using multiple conditions.

function checkLeapYear(year) {
  if (year % 4 == 0 && year % 100 != 0) {
    if (year % 400 == 0) console.log(`${year} is a leap year`);
  } else console.log(`${year} is not a leap year`);
}

Usage:

checkLeapYear(7126);  // Output: 7126 is not a leap year

Output

JavaScript Day 4 Loops by Hitesh Sir

For Loop

Task 1: Print numbers from 1 to 10

for (var i = 1; i <= 10; i++) {
  console.log(i);
}


This code uses a `for` loop to print numbers from 1 to 10. The loop initializes `i` to 1, continues as long as `i` is less than or equal to 10, and increments `i` by 1 in each iteration.

### Task 2: Print multiplication table of 5

```javascript
for (var i = 1; i <= 10; i++) {
  console.log(i * 5);
}

This code prints the multiplication table of 5 up to 10. It uses a for loop similar to Task 1, but multiplies each number by 5 before printing.

While Loop

Task 3: Calculate sum of numbers from 1 to 10

var sum = 0;
var sum_num = 1;
while (sum_num <= 10) {
  sum += sum_num;
  sum_num++;
}
console.log(sum, "this is sum");

This code uses a while loop to calculate the sum of numbers from 1 to 10. It initializes sum to 0 and sum_num to 1, then adds sum_num to sum in each iteration until sum_num exceeds 10.

Task 4: Print numbers from 10 to 1

var i = 10;
while (i > 0) {
  console.log(i);
  i--;
}

This code prints numbers from 10 to 1 using a while loop. It initializes i to 10 and decrements it in each iteration until it reaches 0.

Do...While Loop

Task 5: Print numbers from 1 to 5

var number3_5 = 1;
do {
  console.log(number3_5);
  number3_5++;
} while (number3_5 <= 5);

This code uses a do...while loop to print numbers from 1 to 5. The loop body is executed at least once before the condition is checked.

Task 6: Calculate factorial of a number

function factorial(num) {
  var fact = 1;
  var i = 1;
  do {
    fact *= i;
    i++;
  } while (i <= num);
  console.log(fact);
}
factorial(5);

This function calculates the factorial of a given number using a do...while loop. It multiplies numbers from 1 to the given number and returns the result.

Nested Loops

Task 7: Print a pattern

for (var i = 1; i <= 5; i++) {
  var str = "";
  for (var j = 1; j <= i; j++) {
    str += "* ";
  }
  console.log(str);
}

This code uses nested for loops to print a triangular pattern of asterisks. The outer loop controls the number of rows, while the inner loop prints the asterisks for each row.

Loop Control Statements

Task 8: Skip number 5 using continue

for (var i = 1; i <= 10; i++) {
  if (i === 5) continue;
  console.log(i);
}

This code prints numbers from 1 to 10, but skips the number 5 using the continue statement. When i is 5, the continue statement skips the rest of the loop body and moves to the next iteration.

Task 9: Stop at number 7 using break

for (var i = 1; i <= 10; i++) {
  if (i === 7) break;
  console.log(i);
}

This code prints numbers from 1 to 10, but stops the loop when the number is 7 using the break statement. When i is 7, the break statement terminates the loop entirely.

Did you find this article valuable?

Support Ankit Mishra by becoming a sponsor. Any amount is appreciated!