50 JavaScript exercises along with their solutions

50 JavaScript exercises along with their solutions:

Exercise 1:
Write a program to display “Hello, World!” in the console.

console.log("Hello, World!");

Exercise 2:
Write a program to add two numbers and display the result.

let num1 = 5;
let num2 = 10;
let sum = num1 + num2;
console.log(sum);

Exercise 3:
Write a program to check if a number is positive, negative, or zero.

let number = 0;

if (number > 0) {
  console.log("Positive");
} else if (number < 0) {
  console.log("Negative");
} else {
  console.log("Zero");
}

Exercise 4:
Write a program to check if a number is even or odd.

let number = 7;

if (number % 2 === 0) {
  console.log("Even");
} else {
  console.log("Odd");
}

Exercise 5:
Write a program to find the maximum of two numbers.

let num1 = 10;
let num2 = 5;

let max = num1 > num2 ? num1 : num2;
console.log(max);

Exercise 6:
Write a program to find the minimum of two numbers.

let num1 = 10;
let num2 = 5;

let min = num1 < num2 ? num1 : num2;
console.log(min);

Exercise 7:
Write a program to check if a year is a leap year.

let year = 2020;

if ((year % 4 === 0 && year % 100 !== 0) || year % 400 === 0) {
  console.log("Leap year");
} else {
  console.log("Not a leap year");
}

Exercise 8:
Write a program to check if a string is empty or not.

let str = "";

if (str === "") {
  console.log("String is empty");
} else {
  console.log("String is not empty");
}

Exercise 9:
Write a program to check if a string is a palindrome.

let str = "madam";
let reversedStr = str.split("").reverse().join("");

if (str === reversedStr) {
  console.log("Palindrome");
} else {
  console.log("Not a palindrome");
}

Exercise 10:
Write a program to reverse a string.

let str = "Hello, World!";
let reversedStr = str.split("").reverse().join("");
console.log(reversedStr);

Exercise 11:
Write a program to find the factorial of a number.

let num = 5;
let factorial = 1;

for (let i = 1; i <= num; i++) {
  factorial *= i;
}

console.log(factorial);

Exercise 12:
Write a program to generate Fibonacci series up to a given number of terms.

let numTerms = 10;
let fibonacciSeries = [0, 1];

for (let i = 2; i < numTerms; i++) {
  let nextTerm = fibonacciSeries[i - 1] + fibonacciSeries[i - 2];
  fibonacciSeries.push(nextTerm);
}

console.log(fibonacciSeries);

Exercise 13:
Write a program to check if a number is a prime number.

let num = 17;
let isPrime = true;

for (let i = 2; i <= Math.sqrt(num); i++) {
  if (num % i === 

0) {
    isPrime = false;
    break;
  }
}

if (isPrime) {
  console.log("Prime number");
} else {
  console.log("Not a prime number");
}

Exercise 14:
Write a program to find the sum of all elements in an array.

let numbers = [1, 2, 3, 4, 5];
let sum = 0;

for (let i = 0; i < numbers.length; i++) {
  sum += numbers[i];
}

console.log(sum);

Exercise 15:
Write a program to find the maximum element in an array.

let numbers = [1, 5, 3, 9, 2];
let max = numbers[0];

for (let i = 1; i < numbers.length; i++) {
  if (numbers[i] > max) {
    max = numbers[i];
  }
}

console.log(max);

Exercise 16:
Write a program to remove duplicate elements from an array.

let numbers = [1, 2, 3, 2, 4, 1, 5, 4];
let uniqueNumbers = [];

for (let i = 0; i < numbers.length; i++) {
  if (!uniqueNumbers.includes(numbers[i])) {
    uniqueNumbers.push(numbers[i]);
  }
}

console.log(uniqueNumbers);

Exercise 17:
Write a program to count the number of vowels in a string.

let str = "Hello, World!";
let vowels = ["a", "e", "i", "o", "u"];
let count = 0;

for (let i = 0; i < str.length; i++) {
  if (vowels.includes(str[i].toLowerCase())) {
    count++;
  }
}

console.log(count);

Exercise 18:
Write a program to count the number of words in a string.

let str = "Hello, World!";
let words = str.split(" ");
let count = words.length;

console.log(count);

Exercise 19:
Write a program to check if a string is a valid email address.

let email = "test@example.com";
let regex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;

if (regex.test(email)) {
  console.log("Valid email address");
} else {
  console.log("Invalid email address");
}

Exercise 20:
Write a program to reverse the order of words in a string.

let str = "Hello, World!";
let reversedWords = str.split(" ").reverse().join(" ");

console.log(reversedWords);

Exercise 21:
Write a program to find the length of the longest word in a string.

let str = "Hello, World!";
let words = str.split(" ");
let maxLength = 0;

for (let i = 0; i < words.length; i++) {
  if (words[i].length > maxLength) {
    maxLength = words[i].length;
  }
}

console.log(maxLength);

Exercise 22:
Write a program to sort an array of numbers in ascending order.

let numbers = [5, 2, 9, 1, 7];
numbers.sort((a, b) => a - b);

console.log(numbers);

Exercise 23:
Write a program to sort an array of strings in alphabetical order.

let fruits = ["Apple", "Orange", "Banana", "Mango"];
fruits.sort();

console.log(fruits);

Exercise 24:
Write a program to check if two strings are an

agrams.

let str1 = "listen";
let str2 = "silent";

let sortedStr1 = str1.toLowerCase().split("").sort().join("");
let sortedStr2 = str2.toLowerCase().split("").sort().join("");

if (sortedStr1 === sortedStr2) {
  console.log("Anagrams");
} else {
  console.log("Not anagrams");
}

Exercise 25:
Write a program to find the sum of natural numbers up to a given number.

let num = 10;
let sum = 0;

for (let i = 1; i <= num; i++) {
  sum += i;
}

console.log(sum);

Exercise 26:
Write a program to find the factorial of a number using recursion.

function factorial(num) {
  if (num === 0) {
    return 1;
  } else {
    return num * factorial(num - 1);
  }
}

console.log(factorial(5));

Exercise 27:
Write a program to check if a string is a valid palindrome ignoring spaces and punctuation.

function isPalindrome(str) {
  let regex = /[^\w]|_/g;
  let cleanedStr = str.toLowerCase().replace(regex, "");
  let reversedStr = cleanedStr.split("").reverse().join("");

  return cleanedStr === reversedStr;
}

console.log(isPalindrome("A man, a plan, a canal, Panama!"));

Exercise 28:
Write a program to convert a string to title case.

function toTitleCase(str) {
  let words = str.split(" ");
  let titleCaseWords = [];

  for (let i = 0; i < words.length; i++) {
    let word = words[i];
    let titleCaseWord = word.charAt(0).toUpperCase() + word.slice(1).toLowerCase();
    titleCaseWords.push(titleCaseWord);
  }

  return titleCaseWords.join(" ");
}

console.log(toTitleCase("hello, world!"));

Exercise 29:
Write a program to find the second largest element in an array.

let numbers = [5, 2, 9, 1, 7];
numbers.sort((a, b) => b - a);

console.log(numbers[1]);

Exercise 30:
Write a program to remove all falsy values from an array.

let array = [0, 1, false, true, "", "hello", null, undefined, NaN];
let filteredArray = array.filter(Boolean);

console.log(filteredArray);

Exercise 31:
Write a program to find the median of an array of numbers.

let numbers = [5, 2, 9, 1, 7];
numbers.sort((a, b) => a - b);

let median;

if (numbers.length % 2 === 0) {
  let midIndex = numbers.length / 2;
  median = (numbers[midIndex - 1] + numbers[midIndex]) / 2;
} else {
  let midIndex = Math.floor(numbers.length / 2);
  median = numbers[midIndex];
}

console.log(median);

Exercise 32:
Write a program to find the sum of all even numbers in an array.

let numbers = [1, 2, 3, 4, 5];
let sum = 0;

for (let i = 0; i < numbers.length; i++) {
  if (numbers[i] % 2 === 0) {
    sum += numbers[i];
  }
}

console.log(sum);

Exercise 33:
Write a program to find the intersection of two arrays

.

let array1 = [1, 2, 3, 4, 5];
let array2 = [4, 5, 6, 7, 8];
let intersection = [];

for (let i = 0; i < array1.length; i++) {
  if (array2.includes(array1[i])) {
    intersection.push(array1[i]);
  }
}

console.log(intersection);

Exercise 34:
Write a program to convert a number to binary.

let num = 10;
let binary = num.toString(2);

console.log(binary);

Exercise 35:
Write a program to convert a binary number to decimal.

let binary = "1010";
let decimal = parseInt(binary, 2);

console.log(decimal);

Exercise 36:
Write a program to find the sum of digits of a number.

let num = 12345;
let sum = 0;

while (num > 0) {
  sum += num % 10;
  num = Math.floor(num / 10);
}

console.log(sum);

Exercise 37:
Write a program to find the largest element in an array using reduce() method.

let numbers = [5, 2, 9, 1, 7];
let max = numbers.reduce((a, b) => Math.max(a, b));

console.log(max);

Exercise 38:
Write a program to find the smallest element in an array using reduce() method.

let numbers = [5, 2, 9, 1, 7];
let min = numbers.reduce((a, b) => Math.min(a, b));

console.log(min);

Exercise 39:
Write a program to remove duplicate elements from an array using the filter() method.

let numbers = [1, 2, 3, 2, 4, 1, 5, 4];
let uniqueNumbers = numbers.filter((value, index, array) => array.indexOf(value) === index);

console.log(uniqueNumbers);

Exercise 40:
Write a program to find the average of numbers in an array.

let numbers = [1, 2, 3, 4, 5];
let sum = numbers.reduce((a, b) => a + b);
let average = sum / numbers.length;

console.log(average);

Exercise 41:
Write a program to shuffle an array.

let array = [1, 2, 3, 4, 5];

for (let i = array.length - 1; i > 0; i--) {
  let j = Math.floor(Math.random() * (i + 1));
  [array[i], array[j]] = [array[j], array[i]];
}

console.log(array);

Exercise 42:
Write a program to find the number of occurrences of a specific element in an array.

let array = [1, 2, 3, 2, 4, 1, 5, 4];
let element = 2;
let count = array.reduce((acc, value) => (value === element ? acc + 1 : acc), 0);

console.log(count);

Exercise 43:
Write a program to check if a number is a perfect number.

function isPerfectNumber(num) {
  let sum = 0;

  for (let i = 1; i < num; i++) {
    if (num % i === 0) {
      sum += i;
    }
  }

  return sum === num;
}

console.log(is

PerfectNumber(28));

Exercise 44:
Write a program to find the power of a number.

function power(base, exponent) {
  let result = 1;

  for (let i = 0; i < exponent; i++) {
    result *= base;
  }

  return result;
}

console.log(power(2, 3));

Exercise 45:
Write a program to find the number of words in a sentence.

let sentence = "Hello, World!";
let words = sentence.split(" ");
let count = words.length;

console.log(count);

Exercise 46:
Write a program to find the sum of digits of a number using recursion.

function sumOfDigits(num) {
  if (num === 0) {
    return 0;
  } else {
    return (num % 10) + sumOfDigits(Math.floor(num / 10));
  }
}

console.log(sumOfDigits(12345));

Exercise 47:
Write a program to find the GCD (Greatest Common Divisor) of two numbers.

function gcd(a, b) {
  if (b === 0) {
    return a;
  } else {
    return gcd(b, a % b);
  }
}

console.log(gcd(12, 18));

Exercise 48:
Write a program to convert a decimal number to binary using recursion.

function decimalToBinary(num) {
  if (num === 0) {
    return "";
  } else {
    return decimalToBinary(Math.floor(num / 2)) + (num % 2);
  }
}

console.log(decimalToBinary(10));

Exercise 49:
Write a program to find the LCM (Least Common Multiple) of two numbers.

function lcm(a, b) {
  let max = Math.max(a, b);
  let min = Math.min(a, b);

  for (let i = max; ; i += max) {
    if (i % min === 0) {
      return i;
    }
  }
}

console.log(lcm(12, 18));

Exercise 50:
Write a program to find the number of digits in a number.

let num = 12345;
let count = num.toString().length;

console.log(count);