1.Reverse a String:
Write a function that takes a string as input and returns the string reversed. For example, if the input is “hello”, the output should be “olleh”.
function reverseString(str) {
return str.split('').reverse().join('');
}
console.log(reverseString('hello'));
// Output: 'olleh'
2.Check for Palindrome:
Write a function that takes a string as input and returns true if the string is a palindrome (reads the same forwards and backwards), and false otherwise..
function isPalindrome(str) {
const reversed = str.split('')
.reverse().join('');
return str === reversed;
}
console.log(isPalindrome('racecar'));
// Output: true
3.Find the Maximum Number in an Array:
Write a function that takes an array of numbers as input and returns the maximum number in the array.
function findMax(arr) {
return Math.max(...arr);
}
console.log(findMax([3, 6, 2, 8, 1]));
// Output: 8
4.Calculate Factorial of a Number:
Write a function that takes a number as input and returns the factorial of that number. The factorial of a non-negative integer n is the product of all positive integers less than or equal to n.
function factorial(n) {
if (n === 0 || n === 1) return 1;
return n * factorial(n - 1);
}
console.log(factorial(5));
// Output: 120
5.Check for Prime Number:
Write a function that takes a number as input and returns true if the number is prime (greater than 1 and divisible only by 1 and itself), and false otherwise.
function isPrime(n) {
if (n <= 1) return false;
for (let i = 2; i <= Math.sqrt(n); i++) {
if (n % i === 0) return false;
}
return true;
}
console.log(isPrime(11));
// Output: true
6.Remove Duplicates from an Array:
Write a function that takes an array as input and returns a new array with duplicate elements removed, preserving the original order.
function removeDuplicates(arr) {
return Array.from(new Set(arr));
}
console.log(removeDuplicates([1, 2, 2, 3, 4, 4, 5]));
// Output: [1, 2, 3, 4, 5]
7.Check for Armstrong Number:
Write a function that takes a number as input and returns true if the number is an Armstrong number, and false otherwise. An Armstrong number (also known as narcissistic number) is a number that is equal to the sum of its own digits raised to the power of the number of digits.
function isArmstrong(num) {
const digits = String(num).split('');
const n = digits.length;
const sum = digits.reduce((acc, digit)
=> acc + Math.pow(parseInt(digit), n), 0);
return sum === num;
}
console.log(isArmstrong(153));
// Output: true
8.Calculate Fibonacci Series:
Write a function that takes a number n as input and returns an array containing the first n numbers of the Fibonacci sequence. Each number in the Fibonacci sequence is the sum of the two preceding numbers.
function fibonacci(n) {
const fib = [0, 1];
for (let i = 2; i < n; i++) {
fib.push(fib[i - 1] + fib[i - 2]);
}
return fib;
}
console.log(fibonacci(5));
// Output: [0, 1, 1, 2, 3]
9.Check for Anagrams:
Write a function that takes two strings as input and returns true if the strings are anagrams of each other (contain the same characters in a different order), and false otherwise.
function isAnagram(str1, str2) {
return str1.split('').sort().join('')
=== str2.split('').sort().join('');
}
console.log(isAnagram('listen', 'silent'));
// Output: true
10.Check for Armstrong Numbers in a Range:
Write a function that takes two numbers min and max as input and returns an array containing all Armstrong numbers in the range from min to max (inclusive).
function armstrongInRange(min, max) {
const armstrongNumbers = [];
for (let i = min; i <= max; i++) {
let sum = 0;
let temp = i;
const n = String(i).length;
while (temp > 0) {
const digit = temp % 10;
sum += digit ** n;
temp = Math.floor(temp / 10);
}
if (sum === i) armstrongNumbers.push(i);
}
return armstrongNumbers;
}
console.log(armstrongInRange(100, 1000));
// Output: [153, 370, 371, 407]
